Discrete polarization state rotatable compensator spectroscopic ellipsometer system, and method of calibration

ABSTRACT

Disclosed are spectroscopic ellipsometer and combined spectroscopic reflectometer/ellipsometer systems. The spectroscopic ellipsometer system portion includes polarizer and analyzer elements which remain fixed in position during data acquisition, and a step-wise rotatable compensator electromagnetic beam transmitting means, which serves to enable imposing a plurality of sequentially discrete, rather than continuously varying, polarization states on said beam of electromagnetic radiation. Further disclosed is a calibration procedure for said spectroscopic ellipsometer system portion of the invention which involves the gathering of, for each of a plurality of ellipsometrically distinct sample systems, spectroscopic data at a sequential plurality of discrete electromagnetic radiation beam polarization states, combined with providing of a mathematical model of the spectroscopic ellipsometer system and application of a mathematical regression procedure.

This application is a Continuation-In-Part of Provisional ApplicationSer. No. 60/229,755 filed Sep. 5, 2000. This Application is also aContinuation-in-Part of application Ser. No. 09/517,125 filed Feb. 29,2000, now abandoned, and of application Ser. No. 09/246,888 filed Feb.8, 1999 now U.S. Pat. No. 6,084,675. Further, via the Ser. No.09/246,888 Application, this application is a Continuation-In-Part ofapplication Ser. No. 08/912,211 filed Aug. 15, 1997, (now U.S. Pat. No.5,872,630), which was a CIP from application Ser. No. 08/530,892 filedSep. 20, 1995, (now U.S. Pat. No. 5,666,201); and is a CIP ofapplication Ser. No. 08/618,820 filed Mar. 20, 1996, (now U.S. Pat. No.5,706,212). This Application is further a CIP of Co-Pending applicationSer. Nos. 09/225,118; 09/223,822; 09/232,257; 09/225,371; 09/225,076each filed Jan. 19, 1999 which Applications depend from application Ser.No. 08/997,311 filed Dec. 23, 1997, now U.S. Pat. No. 5,946,098. Inaddition, priority is Claimed from patent application Ser. No.09/162,217 filed Sep. 29, 1998.

TECHNICAL FIELD

The present invention relates to ellipsometer and combinedreflectometer/ellipsometer systems, as well as methods of calibrationtherefore. More particularly the present invention comprises, in theellipsometer portion, provision for providing a sequential plurality oftransmissive, stepwise rotated, compensator positions rather thancontinuously varying, polarization states. The present inventioncombined spectroscopic reflectometer/ellipsometer system preferablyincludes system integration via the sharing of a source of spectroscopicelectromagnetic radiation and/or the sharing of a spectroscopicmulti-element detector system between ellipsometer and reflectometersystem portions. The present invention further comprises a calibrationprocedure for said spectroscopic ellipsometer system which involves thegathering of, for each of a plurality of investigated sample systems,spectroscopic data at a sequential plurality of discrete polarizationstates.

BACKGROUND

The practice of ellipsometry is well established as a non-destructiveapproach to determining characteristics of sample systems, and can bepracticed in real time. The topic is well described in a number ofpublications, one such publication being a review paper by Collins,titled “Automatic Rotating Element Ellipsometers: Calibration, Operationand Real-Time Applications”, Rev. Sci. Instrum., 61(8) (1990).

In general, modern practice of ellipsometry typically involves causing aspectroscopic beam of electromagnetic radiation, in a known state ofpolarization, to interact with a sample system at at least one angle ofincidence with respect to a normal to a surface thereof, in a plane ofincidence. (Note, a plane of incidence contains both a normal to asurface of an investigated sample system and the locus of said beam ofelectromagnetic radiation). Changes in the polarization state of saidbeam of electromagnetic radiation which occur as a result of saidinteraction with said sample system are indicative of the structure andcomposition of said sample system. The practice of ellipsometry furtherinvolves proposing a mathematical model of the ellipsometer system andthe sample system investigated by use thereof, and experimental data isthen obtained by application of the ellipsometer system. This istypically followed by application of a square error reducingmathematical regression to the end that parameters in the mathematicalmodel which characterize the sample system are evaluated, such that theobtained experimental data, and values calculated by use of themathematical model, are essentially the same.

A typical goal in ellipsometry is to obtain, for each wavelength in, andangle of incidence of said beam of electromagnetic radiation caused tointeract with a sample system, sample system characterizing PSI andDELTA values, (where PSI is related to a change in a ratio of magnitudesof orthogonal components r_(p)/r_(s) in said beam of electromagneticradiation, and wherein DELTA is related to a phase shift entered betweensaid orthogonal components r_(p) and r_(s)), caused by interaction withsaid sample system:PSI=|r _(p) /r _(s)|; andDELTA=(Δr _(p) −Δ _(s)).

As alluded to, the practice of ellipsometry requires that a mathematicalmodel be derived and provided for a sample system and for theellipsometer system being applied. In that light it must be appreciatedthat an ellipsometer system which is applied to investigate a samplesystem is, generally, sequentially comprised of:

a. a Source of a beam electromagnetic radiation;

b. a Polarizer element;

c. optionally a compensator element;

d. (additional element(s));

e. a sample system;

f. (additional element(s));

g. optionally a compensator element;

h. an Analyzer element; and

i. a Spectroscopic Detector System.

Each of said components b.–i. must be accurately represented by amathematical model of the ellipsometer system along with a vector whichrepresents a beam of electromagnetic radiation provided from said sourceof a beam electromagnetic radiation, Identified in a. above)

Various conventional ellipsometer configurations provide that aPolarizer, Analyzer and/or Compensator(s) can be rotated during dataacquisition, and are describe variously as Rotating Polarizer (RPE),Rotating Analyzer (RAE) and Rotating Compensator (RCE) EllipsometerSystems. As described elsewhere in this Specification, the presentinvention breaks with this convention and provides that no element becontinuously rotated during data acquisition but rather that a sequenceof discrete polarization states be imposed during data acquisition. Thisapproach allows eliminating many costly components from conventionalrotating element ellipsometer systems, and, hence, production of an“Ultra-Low-Cost” ellipsometer system. It is noted, that nullingellipsometers also exist in which elements therein are rotatable in use,rather than rotating. Generally, use of a nulling ellipsometer systeminvolves imposing a linear polarization state on a beam ofelectromagnetic radiation with a polarizer, causing the resultingpolarized beam of electromagnetic radiation to interact with a samplesystem, and then adjusting an analyzer to an azimuthal azimuthal anglewhich effectively cancels out the beam of electromagnetic radiationwhich proceeds past the sample system. The azimuthal angle of theanalyzer at which nulling occurs provides insight to properties of thesample system.

It is further noted that reflectometer systems are generallysequentially comprised of:

a. a Source of a beam electromagnetic radiation;

d. (optional additional element(s));

e. a sample system;

f. (optional additional element(s));

i. a Spectroscopic Detector System;

and that reflectometer systems monitor changes in intensity of a beam ofelectromagnetic radiation caused to interact with a sample system. Thatis, the ratio of, and phase angle between, orthogonal components in apolarized beam are not of direct concern.

Continuing, in use, data sets can be obtained with an ellipsometersystem configured with a sample system present, sequentially for caseswhere other sample systems are present, and where an ellipsometer systemis configured in a straight-through configuration wherein a beam ofelectromagnetic radiation is caused to pass straight through theellipsometer system without interacting with a sample system.Simultaneous mathematical regression utilizing multiple data sets canallow evaluation of sample system characterizing PSI and DELTA valuesover a range of wavelengths. The obtaining of numerous data sets with anellipsometer system configured with, for instance, a sequence of samplesystems present and/or wherein a sequential plurality of polarizationstates are imposed on an electromagnetic beam caused to interacttherewith, can allow system calibration of numerous ellipsometer systemvariables.

Patents of which the Inventor is aware include those to Woollam et al,U.S. Pat. No. 5,373,359, Patent to Johs et al. U.S. Pat. No. 5,666,201and Patent to Green et al., U.S. Pat. No. 5,521,706, and Patent to Johset al., U.S. Pat. No. 5,504,582 are disclosed for general information asthey pertain to ellipsometer systems.

Further Patents of which the Inventor is aware include U.S. Pat. Nos.5,757,494 and 5,956,145 to Green et al., in which are taught a methodfor extending the range of Rotating Analyzer/Polarizer ellipsometersystems to allow measurement of DELTA'S near zero (0.0) andone-hundred-eighty (180) degrees, and the extension of modulator elementellipsometers to PSI'S of forty-five (45) degrees. Said Patentsdescribes the presence of a variable, transmissive, bi-refringentcomponent which is added, and the application thereof during dataacquisition to enable the identified capability.

A Patent to Thompson et al. U.S. Pat. No. 5,706,212 is also disclosed asit teaches a mathematical regression based double Fourier seriesellipsometer calibration procedure for application, primarily, incalibrating ellipsometers system utilized in infrared wavelength range.Bi-refringent, transmissive window-like compensators are described aspresent in the system thereof, and discussion of correlation ofretardations entered by sequentially adjacent elements which do notrotate with respect to one another during data acquisition is describedtherein.

A Patent to He et al., U.S. Pat. No. 5,963,327 is disclosed as itdescribes an ellipsometer system which enables providing a polarizedbeam of electromagnetic radiation at an oblique angle-of-incidence to asample system in a small spot area.

A Patent to Johs et al., U.S. Pat. No. 5,872,630 is disclosed as itdescribes an ellipsometer system in which an analyzer and polarizer aremaintained in a fixed in position during data acquisition, while acompensator is caused to continuously rotate.

Patent to Dill et al., U.S. Pat. No. 4,953,232 is disclosed as itdescribes a rotating compensator ellipsometer system.

Patents co-owned with this Application, which Patents Claim variousCompensator Designs recited in Claims herein, and which Patents areincorporated hereinto by reference are:

U.S. Pat. No. 5,946,098 to Johs et al.;

U.S. Pat. No. 5,963,325 to Johs et al.;

U.S. Pat. No. 6,084,674 to Johs et al.;

U.S. Pat. No. 6,084,675 to Herzinger et al.;

U.S. Pat. No. 6,100,981 to Johs et al.;

U.S. Pat. No. 6,118,537 to Johs et al.;

U.S. Pat. No. 6,141,102 to Johs et al.

Patents cited in examination of said Patents included No. 4,556,292 toMathyssek et al. and U.S. Pat. No. 5,475,525 to Tournois et al.

A Patent to Coates et al., U.S. Pat. No. 4,826,321 is disclosed as itdescribes applying a reflected monochromatic beam of plane polarizedelectromagnetic radiation at a Brewster angle of incidence to a samplesubstrate to determine the thickness of a thin film thereupon. ThisPatent also describes calibration utilizing two sample substrates, whichhave different depths of surface coating.

Other Patents which describe use of reflected electromagnetic radiationto investigate sample systems are No. RE 34,783, U.S. Pat. Nos.4,373,817, and 5,045,704 to Coates; and U.S. Pat. No. 5,452,091 toJohnson.

A Patent to Bjork et al., U.S. Pat. No. 4,647,207 is disclosed as itdescribes an ellipsometer system which has provision for sequentiallypositioning a plurality of reflective polarization state modifiers in abeam of electromagnetic radiation. While said 207 Patent mentionsinvestigating a sample system in a transmission mode, no mention orsuggestion is found for utilizing a plurality of transmittingpolarization state modifiers, emphasis added. U.S. Pat. Nos. 4,210,401;4,332,476 and 4,355,903 are also identified as being cited in the 207Patent. It is noted that systems as disclosed in these Patents,(particularly in the 476 Patent), which utilize reflection from anelement to modify a polarization state can, that if such an element isan essential duplicate of an investigated sample and is rotated ninetydegrees therefrom, then the effect of the polarization state modifyingelement on the electromagnetic beam effect is extinguished by thesample.

A Patent to Mansuripur et al., U.S. Pat. No. 4,838,695 is disclosed asit describes an apparatus for measuring reflectivity.

Patents to Rosencwaig et al., U.S. Pat. Nos. 4,750,822 and 5,595,406 arealso identified as they describe systems which impinge electromagneticbeams onto sample systems at oblique angles of incidence. The 406 Patentprovides for use of multiple wavelengths and multiple angles ofincidence. For similar reasons U.S. Pat. No. 5,042,951 to Gold et al. isalso disclosed.

A Patent to Osterberg, U.S. Pat. No. 2,700,918 describes a microscopewith variable means for increasing the visibility of optical images,partially comprised of discrete bi-refringent plates which can bepositioned in the pathway between an eyepiece and an observed object.Other Patents identified in a Search which identified said 918 Patentare U.S. Pat. No. 3,183,763 to Koester; No. 4,105,338 to Kuroha; U.S.Pat. No. 3,992,104 to Watanabe and a Russian Patent, No. SU 1518728.Said other Patents are not believed to be particularly relevant,however.

A Patent, U.S. Pat. No. 5,329,357 to Bernoux et al. is also identifiedas it Claims use of fiber optics to carry electromagnetic radiation toand from an ellipsometer system which has at least one polarizer oranalyzer which rotates during data acquisition. It is noted that if boththe polarizer and analyzer are stationary during data acquisition thatthis Patent is not controlling where electromagnetic radiation carryingfiber optics are present.

A Patent to Chen et al., U.S. Pat. No. 5,581,350, is disclosed as itdescribes a method for regression calibration of ellipsometers.

As present invention preferred practice is to utilize a spectroscopicsource of electromagnetic radiation with a relatively flat spectrum overa large range of wavelengths Patent U.S. Pat. No. 6,628,917 to Johs isdisclosed. Patents relevant thereto include U.S. Pat. No. 5,179,462 toKageyama et al. is identified as it provides a sequence of threeelectromagnetic beam combining dichroic mirrors in an arrangement whichproduces an output beam of electromagnetic radiation that containswavelengths from each of four sources of electromagnetic radiation. Eachelectromagnetic beam combining dichroic mirror is arranged so as totransmit a first input beam of electromagnetic radiation, comprising atleast a first wavelength content, therethrough so that it exits a secondside of said electromagnetic beam combining dichroic mirror, and toreflect a second beam of electromagnetic radiation, comprising anadditional wavelength content, from said second side of saidelectromagnetic beam combining dichroic mirror in a manner that a singleoutput beam of electromagnetic radiation is formed which contains thewavelength content of both sources of electromagnetic radiation. Thesources of electromagnetic radiation are described as lasers in said 462Patent. Another Patent, U.S. Pat. No. 5,296,958 to Roddy et al.,describes a similar system which utilizes Thompson Prisms to similarlycombine electromagnetic beams for laser source. U.S. Pat. Nos. 4,982,206and 5,113,279 to Kessler et al. and Hanamoto et al. respectively,describe similar electromagnetic electromagnetic beam combinationsystems in laser printer and laser beam scanning systems respectively.Another Patent, U.S. Pat. No. 3,947,688 to Massey, describes a method ofgenerating tuneable coherent ultraviolet light, comprising use of anelectromagnetic electromagnetic beam combining system. A Patent toMiller et al., U.S. Pat. No. 5,155,623, describes a system for combininginformation beams in which a mirror comprising alternating regions oftransparent and reflecting regions is utilized to combine transmittedand reflected beams of electromagnetic radiation into a single outputbeam. A Patent to Wright, U.S. Pat. No. 5,002,371 is also mentioned asdescribing a beam splitter system which operates to separate “P” and “S”orthogonal components in a beam of polarized electromagnetic radiation.

In addition to the identified Patents, certain Scientific papers arealso identified.

A paper by Johs, titled “Regression Calibration Method for RotatingElement Ellipsometers”, Thin Solid Films, 234 (1993) is also disclosedas it describes a mathematical regression based approach to calibratingellipsometer systems.

Another paper, by Gottesfeld et al., titled “Combined Ellipsometer andReflectometer Measurements of Surface Processes on Nobel MetalsElectrodes”, Surface Sci., 56 (1976), is also identified as describingthe benefits of combining ellipsometry and reflectometry.

A paper by Smith, titled “An Automated Scanning Ellipsometer”, SurfaceScience, Vol. 56, U.S. Pat. No. 1. (1976), is also mentioned as itdescribes an ellipsometer system which does not require any moving, (eg.rotating), elements during data acquisition.

Four additional papers by Azzam and Azzam et al. are also identified andare titled:

-   -   “Multichannel Polarization State Detectors For Time-Resolved        Ellipsometry”, Thin Solid Film, 234 (1993); and    -   “Spectrophotopolarimeter Based On Multiple Reflections In A        Coated Dielectric Slab”, Thin Solid Films 313 (1998); and    -   “General Analysis And Optimization Of The Four-Detector        Photopolarimeter”, J. Opt. Soc. Am., A, Vol. 5, No. 5 (May        1988); and    -   “Accurate Calibration Of Four-Detector Photopolarimeter With        Imperfect Polarization Optical Elements”, J. Opt. Soc. Am., Vol.        6, No. 10, (October 1989);        as they describe alternative approaches concerning the goal of        the present invention.

Even in view of relevant prior art, there remains need for aspectroscopic ellipsometer system which:

-   -   presents with stationary polarizer and analyzer during data        acquisition; and    -   utilizes a plurality of transmissive step-wise rotatable        compensator means to effect a plurality of sequential discrete,        rather than continuously varying, polarization states during        said data acquisition; and    -   which allows optional integrated combination with a        reflectometer system via the sharing of a source of        spectroscopic electromagnetic radiation and/or a spectroscopic        multi-element detector system therewith.

In addition there remains need for a calibration procedure for aspectroscopic ellipsometer system which involves the gathering ofspectroscopic data at a plurality of discrete polarization states foreach of some number of sample systems. The present invention responds tosaid identified needs.

DISCLOSURE OF THE INVENTION

The present invention is, in the first instance, a spectroscopicellipsometer system basically comprising:

-   -   a source of polychromatic electromagnetic radiation;    -   a polarizer which is fixed in position during data acquisition;    -   a stage for supporting a sample system;    -   an analyzer which is fixed in position during data acquisition;        and    -   a multi-element spectroscopic detector system.

In addition, the present invention ellipsometer system further comprisesat least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation through aplurality of polarization states. The at least one means for discretely,sequentially, modifying a polarization state of a beam ofelectromagnetic radiation through a plurality of polarization states, ispositioned between said polarizer and said stage for supporting a samplesystem, and/or and between said stage for supporting a sample system andsaid analyzer, and so that said beam of electromagnetic radiationtransmits through a polarization state modifier element thereof in use.The present invention at least one means for discretely, sequentially,modifying a polarization state of a beam of electromagnetic radiationthrough a plurality of polarization states comprises a compensator whichis mounted to allow step-wise rotation about the locus of a beam ofelectromagentic radiation caused to pass therethrough.

The present invention is further a combination spectroscopicreflectometer/ellipsometer system basically comprising:

a source of polychromatic electromagnetic radiation;

a stage for supporting a sample system;

a multi-element spectroscopic detector system.

The combination spectroscopic reflectometer/ellipsometer system furthercomprises, in the ellipsometer system portion thereof, a polarizer,(which is fixed in position during data acquisition), present betweenthe source of polychromatic electromagnetic radiation and the stage forsupporting a sample system, and an analyzer, (which is fixed in positionduring data acquisition), present between the stage for supporting asample system and the multi-element spectroscopic detector system. Theellipsometer system also comprises at least one means for discretely,sequentially, modifying a polarization state of a beam ofelectromagnetic radiation through a plurality of polarization statespresent between said polarizer and said stage for supporting a samplesystem, and/or between said stage for supporting a sample system andsaid analyzer, and positioned so that said beam of electromagneticradiation transmits through a polarization state modifier elementtherein during use.

Additionally, the combination spectroscopic reflectometer/ellipsometersystem is configured such that a polychromatic beam of electromagneticradiation provided by said source of polychromatic electromagneticradiation can, optionally, be directed to interact with a sample systempresent on said stage for supporting a sample system without anypolarization state being imposed thereupon, and such that apolychromatic beam of electromagnetic radiation also provided by saidsource of polychromatic electromagnetic radiation can be, optionallysimultaneously, directed to interact with a sample system present onsaid stage for supporting a sample system after a polarization state hasbeen imposed thereupon. The polychromatic beam of electromagneticradiation without any polarization state imposed thereupon, whendirected to interact with a sample system present on said stage forsupporting a sample system, is typically caused to approach said samplesystem at an oblique angle-of-incidence which is between a sample systemBrewster angle and a normal to the surface of the sample system.Further, the polychromatic beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation upon which apolarization state has been imposed, is typically directed to interactwith a sample system present on said stage for supporting a samplesystem at an angle near the Brewster angle of the sample system beinginvestigated. Either, or both, the polychromatic beam(s) ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation, upon which is imposed a polarization state orupon which no polarization state is imposed, is preferably directed tointeract with a sample system present on said stage for supporting asample system via a fiber optic means.

While the present invention can utilize essentially any Compensator, apreferred embodiment of the present invention provides that at least oneof said at least one compensator(s), which is mounted to allow step-wiserotation about the locus of a beam of electromagentic radiation causedto pass therethrough, be selected from the group consisting of:

-   -   a single element compensator;    -   a compensator system comprised of at least two per se.        zero-order waveplates (MOA) and (MOB), said per se. zero-order        waveplates (MOA) and (MOB) having their respective fast axes        rotated to a position offset from zero or ninety degrees with        respect to one another, with a nominal value being forty-five        degrees;    -   a compensator system comprised of a combination of at least a        first (ZO1) and a second (ZO2) effective zero-order wave plate,        said first (ZO1) effective zero-order wave plate being comprised        of two multiple order waveplates (MOA1) and (MOB1) which are        combined with the fast axes thereof oriented at a nominal ninety        degrees to one another, and said second (ZO2) effective        zero-order wave plate being comprised of two multiple order        waveplates (MOA2) and (MOB2) which are combined with the fast        axes thereof oriented at a nominal ninety degrees to one        another; the fast axes (FAA2) and (FAB2) of the multiple order        waveplates (MOA2) and (MOB2) in said second effective zero-order        wave plate (ZO2) being rotated to a position at a nominal        forty-five degrees to the fast axes (FAA1) and (FAB1),        respectively, of the multiple order waveplates (MOA1) and (MOB1)        in said first effective zero-order waveplate (ZO1);    -   a compensator system comprised of a combination of at least a        first (ZO1) and a second (ZO2) effective zero-order wave plate,        said first (ZO1) effective zero-order wave plate being comprised        of two multiple order waveplates (MOA1) and (MOB1) which are        combined with the fast axes thereof oriented at a nominal ninety        degrees to one another, and said second (ZO2) effective        zero-order wave plate being comprised of two multiple order        waveplates (MOA2) and (MOB2) which are combined with the fast        axes thereof oriented at a nominal ninety degrees to one        another; the fast axes (FAA2) and (FAB2) of the multiple order        waveplates (MOA2) and (MOB2) in said second effective zero-order        wave plate (ZO2) being rotated to a position away from zero or        ninety degrees with respect to the fast axes (FAA1) and (FAB1),        respectively, of the multiple order waveplates (MOA1) and (MOB1)        in said first effective zero-order waveplate (ZO1);    -   a compensator system comprised of at least one zero-order        waveplate, ((MOA) or (MOB)), and at least one effective        zero-order waveplate, ((ZO2) or (ZO1) respectively), said        effective zero-order wave plate, ((ZO2) or (ZO1)), being        comprised of two multiple order waveplates which are combined        with the fast axes thereof oriented at a nominal ninety degrees        to one another, the fast axes of the multiple order waveplates        in said effective zero-order wave plate, ((ZO2) or (ZO1)), being        rotated to a position away from zero or ninety degrees with        respect to the fast axis of the zero-order waveplate, ((MOA) or        (MOB));        where the identifiers are shown in FIGS. 3 e–3 i.

Additional compensator systems, previously disclosed in patentapplication Ser. No. 08/997,311, (now U.S. Pat. No. 5,946,098), andCIP's therefrom, which are specifically within the scope of theinvention and can be included in the selection group are:

-   -   a compensator system comprised of a first triangular shaped        element, which as viewed in side elevation presents with first        and second sides which project to the left and right and        downward from an upper point, which first triangular shaped        element first and second sides have reflective outer surfaces;        said retarder system further comprising a second triangular        shaped element which as viewed in side elevation presents with        first and second sides which project to the left and right and        downward from an upper point, said second triangular shaped        element being made of material which provides reflective        interfaces on first and second sides inside thereof; said second        triangular shaped element being oriented with respect to the        first triangular shaped element such that the upper point of        said second triangular shaped element is oriented essentially        vertically directly above the upper point of said first        triangular shaped element; such that in use an input        electromagnetic beam of radiation caused to approach one of said        first and second sides of said first triangular shaped element        along an essentially horizontally oriented locus, is caused to        externally reflect from an outer surface thereof and travel        along a locus which is essentially upwardly vertically oriented,        then enter said second triangular shaped element and essentially        totally internally reflect from one of said first and second        sides thereof, then proceed along an essentially horizontal        locus and essentially totally internally reflect from the other        of said first and second sides and proceed along an essentially        downward vertically oriented locus, then externally reflect from        the other of said first and second sides of said first        triangular shaped elements and proceed along an essentially        horizontally oriented locus which is undeviated and undisplaced        from the essentially horizontally oriented locus of said input        beam of essentially horizontally oriented electromagnetic        radiation even when said retarder is caused to rotate; with a        result being that retardation is entered between orthogonal        components of said input electromagnetic beam of radiation;    -   a compensator system comprised of, as viewed in upright side        elevation, first and second orientation adjustable mirrored        elements which each have reflective surfaces; said        compensator/retarder system further comprising a third element        which, as viewed in upright side elevation, presents with first        and second sides which project to the left and right and        downward from an upper point, said third element being made of        material which provides reflective interfaces on first and        second sides inside thereof; said third element being oriented        with respect to said first and second orientation adjustable        mirrored elements such that in use an input electromagnetic beam        of radiation caused to approach one of said first and second        orientation adjustable mirrored elements along an essentially        horizontally oriented locus, is caused to externally reflect        therefrom and travel along a locus which is essentially upwardly        vertically oriented, then enter said third element and        essentially totally internally reflect from one of said first        and second sides thereof, then proceed along an essentially        horizontal locus and essentially totally internally reflect from        the other of said first and second sides and proceed along an        essentially downward vertically oriented locus, then reflect        from the other of said first and second orientation adjustable        mirrored elements and proceed along an essentially horizontally        oriented propagation direction locus which is essentially        undeviated and undisplaced from the essentially horizontally        oriented propagation direction locus of said input beam of        essentially horizontally oriented electromagnetic radiation even        when said compensator/retarder is caused to rotate; with a        result being that retardation is entered between orthogonal        components of said input electromagnetic beam of radiation;    -   a compensator system comprised of a parallelogram shaped element        which, as viewed in side elevation, has top and bottom sides        parallel to one another, both said top and bottom sides being        oriented essentially horizontally, said retarder system also        having right and left sides parallel to one another, both said        right and left sides being oriented at an angle to horizontal,        said retarder being made of a material with an index of        refraction greater than that of a surrounding ambient; such that        in use an input beam of electromagnetic radiation caused to        enter a side of said retarder selected from the group consisting        of: (right and left), along an essentially horizontally oriented        locus, is caused to diffracted inside said retarder system and        follow a locus which causes it to essentially totally internally        reflect from internal interfaces of both said top and bottom        sides, and emerge from said retarder system from a side selected        from the group consisting of (left and right respectively),        along an essentially horizontally oriented locus which is        undeviated and undisplaced from the essentially horizontally        oriented locus of said input beam of essentially horizontally        oriented electromagnetic radiation even when said retarder is        caused to rotate; with a result being that retardation is        entered between orthogonal components of said input        electromagnetic beam of radiation;    -   a compensator system comprised of first and second triangular        shaped elements, said first triangular shaped element, as viewed        in side elevation, presenting with first and second sides which        project to the left and right and downward from an upper point,        said first triangular shaped element further comprising a third        side which is oriented essentially horizontally and which is        continuous with, and present below said first and second sides;        and said second triangular shaped element, as viewed in side        elevation, presenting with first and second sides which project        to the left and right and upward from an upper point, said        second triangular shaped element further comprising a third side        which is oriented essentially horizontally and which is        continuous with, and present above said first and second sides;        said first and second triangular shaped elements being        positioned so that a rightmost side of one of said first and        second triangular shaped elements is in contact with a leftmost        side of the other of said first and second triangular shaped        elements over at least a portion of the lengths thereof; said        first and second triangular shaped elements each being made of        material with an index of refraction greater than that of a        surrounding ambient; such that in use an input beam of        electromagnetic radiation caused to enter a side of a triangular        shaped element selected from the group consisting of: (first and        second), not in contact with said other triangular shape        element, is caused to diffracted inside said retarder and follow        a locus which causes it to essentially totally internally        reflect from internal interfaces of said third sides of each of        said first and second triangular shaped elements, and emerge        from a side of said triangular shaped element selected from the        group consisting of: (second and first), not in contact with        said other triangular shape element, along an essentially        horizontally oriented locus which is undeviated and undisplaced        from the essentially horizontally oriented locus of said input        beam of essentially horizontally oriented electromagnetic        radiation even when said retarder is caused to rotate; with a        result being that retardation is entered between orthogonal        components of said input electromagnetic beam of radiation;    -   a compensator system comprised of a triangular shaped element,        which as viewed in side elevation presents with first and second        sides which project to the left and right and downward from an        upper point, said retarder system further comprising a third        side which is oriented essentially horizontally and which is        continuous with, and present below said first and second sides;        said retarder system being made of a material with an index of        refraction greater than that of a surrounding ambient; such that        in use a an input beam of electromagnetic radiation caused to        enter a side of said retarder system selected from the group        consisting of: (first and second), along an essentially        horizontally oriented locus, is caused to diffracted inside said        retarder system and follow a locus which causes it to        essentially totally internally reflect from internal interface        of said third sides, and emerge from said retarder from a side        selected from the group consisting of (second and first        respectively), along an essentially horizontally oriented locus        which is undeviated and undisplaced from the essentially        horizontally oriented locus of said input beam of essentially        horizontally oriented electromagnetic radiation even when said        retarder system is caused to rotate; with a result being that        retardation is entered between orthogonal components of said        input electromagnetic beam of radiation; and    -   a compensator system comprised of first and second Berek-type        retarders which each have an optical axes essentially        perpendicular to a surface thereof, each of which first and        second Berek-type retarders has a fast axis, said fast axes in        said first and second Berek-type retarders being oriented in an        orientation selected from the group consisting of: (parallel to        one another and other than parallel to one another); said first        and second Berek-type retarders each presenting with first and        second essentially parallel sides, and said first and second        Berek-type retarders being oriented, as viewed in side        elevation, with first and second sides of one Berek-type        retarder being oriented other than parallel to first and second        sides of the other Berek-type retarder; such that in use an        incident beam of electromagnetic radiation is caused to impinge        upon one of said first and second Berek-type retarders on one        side thereof, partially transmit therethrough then impinge upon        the second Berek-type retarder, on one side thereof, and        partially transmit therethrough such that a polarized beam of        electromagnetic radiation passing through both of said first and        second Berek-type retarders emerges from the second thereof in a        polarized state with a phase angle between orthogonal components        therein which is different than that in the incident beam of        electromagnetic radiation, and in a propagation direction which        is essentially undeviated and undisplaced from the incident beam        of electromagnetic radiation even when said retarder system is        caused to rotate; with a result being that retardation is        entered between orthogonal components of said input        electromagnetic beam of radiation;    -   a compensator system comprised of first and second Berek-type        retarders which each have an optical axes essentially        perpendicular to a surface thereof, each of which first and        second Berek-type retarders has a fast axis, said fast axes in        said first and second Berek-type retarders being oriented other        than parallel to one another; said first and second Berek-type        retarders each presenting with first and second essentially        parallel sides, and said first and second Berek-type retarders        being oriented, as viewed in side elevation, with first and        second sides of one Berek-type retarder being oriented other        than parallel to first and second sides of the other Berek-type        retarder; such that in use an incident beam of electromagnetic        radiation is caused to impinge upon one of said first and second        Berek-type retarders on one side thereof, partially transmit        therethrough then impinge upon the second Berek-type retarder,        on one side thereof, and partially transmit therethrough such        that a polarized beam of electromagnetic radiation passing        through both of said first and second Berek-type retarders        emerges from the second thereof in a polarized state with a        phase angle between orthogonal components therein which is        different than that in the incident beam of electromagnetic        radiation, and in a propagation direction which is essentially        undeviated and undisplaced from the incident beam of        electromagnetic radiation, said compensator system further        comprising third and forth Berek-type retarders which each have        an optical axes essentially perpendicular to a surface thereof,        each of which third and forth Berek-type retarders has a fast        axis, said fast axes in said third and forth Berek-type        retarders being oriented other than parallel to one another,        said third and forth Berek-type retarders each presenting with        first and second essentially parallel sides, and said third and        forth Berek-type retarders being oriented, as viewed in side        elevation, with first and second sides of one of said third and        forth Berek-type retarders being oriented other than parallel to        first and second sides of said forth Berek-type retarder; such        that in use an incident beam of electromagnetic radiation        exiting said second Berek-type retarder is caused to impinge        upon said third Berek-type retarder on one side thereof,        partially transmit therethrough then impinge upon said forth        Berek-type retarder on one side thereof, and partially transmit        therethrough such that a polarized beam of electromagnetic        radiation passing through said first, second, third and forth        Berek-type retarders emerges from the forth thereof in a        polarized state with a phase angle between orthogonal components        therein which is different than that in the incident beam of        electromagnetic radiation caused to impinge upon the first side        of said first Berek-type retarder, and in a direction which is        essentially undeviated and undisplaced from said incident beam        of electromagnetic radiation even when said retarder system is        caused to rotate; with a result being that retardation is        entered between orthogonal components of said input        electromagnetic beam of radiation;    -   a compensator system comprised of first, second, third and forth        Berek-type retarders which each have an optical axes essentially        perpendicular to a surface thereof, each of which first and        second Berek-type retarders has a fast axis, said fast axes in        said first and second Berek-type retarders being oriented        essentially parallel to one another; said first and second        Berek-type retarders each presenting with first and second        essentially parallel sides, and said first and second Berek-type        retarders being oriented, as viewed in side elevation, with        first and second sides of one Berek-type retarder being oriented        other than parallel to first and second sides of the other        Berek-type retarder; such that in use an incident beam of        electromagnetic radiation is caused to impinge upon one of said        first and second Berek-type retarders on one side thereof,        partially transmit therethrough then impinge upon the second        Berek-type retarder, on one side thereof, and partially transmit        therethrough such that a polarized beam of electromagnetic        radiation passing through both of said first and second        Berek-type retarders emerges from the second thereof in a        polarized state with a phase angle between orthogonal components        therein which is different than that in the incident beam of        electromagnetic radiation, and in a propagation direction which        is essentially undeviated and undisplaced from the incident beam        of electromagnetic radiation; each of which third and forth        Berek-type retarders has a fast axis, said fast axes in said        third and forth Berek-type retarders being oriented essentially        parallel to one another but other than parallel to the fast axes        of said first and second Berek-type retarders, said third and        forth Berek-type retarders each presenting with first and second        essentially parallel sides, and said third and forth Berek-type        retarders being oriented, as viewed in side elevation, with        first and second sides of one of said third and forth Berek-type        retarders being oriented other than parallel to first and second        sides of said forth Berek-type retarder; such that in use an        incident beam of electromagnetic radiation exiting said second        Berek-type retarder is caused to impinge upon said third        Berek-type retarder on one side thereof, partially transmit        therethrough then impinge upon said forth Berek-type retarder on        one side thereof, and partially transmit therethrough such that        a polarized beam of electromagnetic radiation passing through        said first, second, third and forth Berek-type retarders emerges        from the forth thereof in a polarized state with a phase angle        between orthogonal components therein which is different than        that in the incident beam of electromagnetic radiation caused to        impinge upon the first side of said first Berek-type retarder,        and in a direction which is essentially undeviated and        undisplaced from said incident beam of electromagnetic radiation        even when said retarder system is caused to rotate; with a        result being that retardation is entered between orthogonal        components of said input electromagnetic beam of radiation.

It is to be appreciated that the present Application does not applyCompensator(s) in a system which causes continuous rotation thereofduring data acquisition, but rather steps a compensator through a seriesof discrete rotational positions, and holds it stationary whileobtaining data. Further, while not required, the present inventionbenefits from Compensator(s) designed to provide relatively constant,achromatic Polarization State Modification effects over a Spectroscopicrange of wavelengths.

As another previously disclosed, (in Co-Pending application Ser. No.09/517,125), non-limiting example, the spectroscopic ellipsometer systemcan provide at least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, can comprise an essentially circular“wheel” element with a plurality of discrete polarization state modifierelements mounted thereupon, on the perimeter thereof, and projectingperpendicularly to a surface of said essentially circular “wheel”. Theessentially circular “wheel” element further comprises a means forcausing rotation about a normal to said surface thereof, such that inuse said essentially circular “wheel” element is caused to rotate toposition a discrete polarization state modifier element such that thebeam of electromagnetic radiation, provided by said source ofpolychromatic electromagnetic radiation, passes therethrough.

As another previously disclosed, (in Co-Pending application Ser. No.09/517,125), non-limiting example, the spectroscopic ellipsometer systemat least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, can comprise a plurality of discretepolarization state modifier elements mounted on a slider element whichis mounted in a guide providing element. During use sliding the sliderelement to the right or left serves to position a discrete polarizerelement such that said a beam of electromagnetic radiation, provided bysaid source of polychromatic electromagnetic radiation, passestherethrough.

Continuing, again as previously disclosed, (in application Ser. No.09/517,125, now U.S. Pat. No. 6,268,917), it is further noted that asystem for providing an output beam of polychromatic electromagneticradiation which has a relatively broad and flattened Intensity vs.Wavelength characteristic over a wavelength spectrum for use in saidpresent invention systems can be applied in the present inventionsystem. The reason for doing so is to provide an output beam ofpolychromatic electromagnetic radiation which is substantially acomingled composite of a plurality of input beams of polychromaticelectromagnetic radiation which individually do not provide asrelatively broad and flattened a intensity vs. wavelength characteristicover said wavelength spectrum, as does said output comingled compositebeam of polychromatic electromagnetic radiation. The system forproviding an output beam of polychromatic electromagnetic radiation,which has a relatively broad and flattened intensity vs. wavelengthcharacteristic over a wavelength spectrum, comprises:

-   -   a. at least a first and a second source of polychromatic        electromagnetic radiation; and    -   b. at least a first electromagnetic beam combining means        comprising a plate, (eg. uncoated fused silica or glass etc.        such that transmission characteristics thereof are determined by        angle-of-incidence and polarization state of a beam of        electromagnetic radiation).        The at least a first electromagnetic beam combining means is        positioned with respect to said first and second sources of        polychromatic electromagnetic radiation such that a beam of        polychromatic electromagnetic radiation from said first source        of polychromatic electromagnetic radiation passes through said        at least a first electromagnetic beam combining means, and such        that a beam of polychromatic electromagnetic radiation from said        second source of polychromatic electromagnetic radiation        reflects from said at least a first electromagnetic beam        combining means and is comingled with said beam of polychromatic        electromagnetic radiation from said first source of        polychromatic electromagnetic radiation which passes through        said at least a first electromagnetic beam combining means. The        resultant beam of polychromatic electromagnetic radiation        exiting the first electromagnetic beam combining means is        substantially an output beam of polychromatic electromagnetic        radiation which has a relatively broad and flattened intensity        vs. wavelength over a wavelength spectrum, comprising said        comingled composite of a plurality of input beams of        polychromatic electromagnetic radiation which individually do        not provide such a relatively broad and flattened intensity vs.        wavelength over a wavelength spectrum characteristic. Said        system for providing an output beam of polychromatic        electromagnetic radiation which has a relatively broad and        flattened intensity vs. wavelength characteristic over a        wavelength spectrum can also be optionally further characterized        by a third source of polychromatic electromagnetic radiation,        and/or a second electromagnetic beam combining (BCM) means        comprising an uncoated plate, (eg. fused silica or glass etc.        such that transmission characteristics thereof are determined by        angle-of-incidence and polarization state of a beam of        electromagnetic radiation). The second electromagnetic beam        combining means, when present, is positioned with respect to        said comingled beam of polychromatic electromagnetic radiation        which has a relatively broad and flattened intensity vs.        wavelength over a wavelength spectrum and which exits said at        least a first electromagnetic beam combining means, such that it        passes through said second electromagnetic beam combining means.        The second electromagnetic beam combining means is also        positioned with respect to the third source of polychromatic        electromagnetic radiation, (when present), such that a beam of        electromagnetic radiation from said third source of        polychromatic electromagnetic radiation reflects from said        second electromagnetic beam combining means, such that a second        resultant beam of polychromatic electromagnetic radiation which        is substantially an output beam of polychromatic electromagnetic        radiation which has a relatively even more broadened and        flattened intensity vs. wavelength over a wavelength spectrum,        comprising said comingled composite of a plurality of input        beams of polychromatic electromagnetic radiation from said        first, second and third sources, which first, second and third        sources individually do not provide such a relatively even more        broadened and flattened intensity vs. wavelength over a        wavelength spectrum characteristic.

At least one of said first and second, (when present), electromagneticbeam combining means can be pivotally mounted such that, for instance,the angle at which a beam of polychromatic electromagnetic radiationfrom the second source of polychromatic electromagnetic radiationreflects from the at least one electromagnetic beam combining means canbe controlled to place it coincident with the locus of a beam ofpolychromatic electromagnetic radiation transmitted therethrough. Pivotmeans providing two dimensional degrees of rotation freedom arepreferred in this application. Further, where sources of polychromaticelectromagnetic radiation can be moved, the pivot capability can beutilized to allow use of optimum tilts of electromagnetic beam combiningmeans. That is, transmission and reflection characteristics of anelectromagnetic beam combining means vary with the angle of incidence atransmitted or reflected bear makes with respect thereto, and pivotmeans can allow adjusting tilt to optimize said characteristics.

Further, as the polarizer in the present invention spectroscopicellipsometer system remains essentially fixed in position during dataacquisition, it is noted that it is preferable that a source ofelectromagnetic radiation, and/or a present Polarizer or PolarizationState Generator be positioned or configured so as to pass predominately“S” Polarized electromagnetic radiation, as referenced to said beamcombining system. The reason for this is that the split between “S”polarization transmission and reflection components is less, as afunction of wavelength and electromagnetic beam angle-of-incidence tosaid beam combining means, when compared to that of the “P” components.The “P” component is far more affected, particularly around a Brewsterangle condition, hence, where an “S” component, with reference to a beamcombining system, is utilized, it is to be appreciated that variation inintensity of transmitted and reflected beams of electromagneticradiation output from the beam combining system, as functions ofwavelength and the angles of incidence of beams of electromagneticradiation from sources of said transmitted and reflected beams ofelectromagnetic radiation, is minimized, as compared to variation whichoccurs in “P” components.

Before discussing the Method of Calibration of the present inventionspectroscopic ellipsometer system, it is noted that the polarizer andanalyzer thereof, which are essentially fixed in position during dataacquisition, are not necessarily absolutely fixed in position. Saidpolarizer and analyzer are preferably what is properly termed“Rotatable”. That is they can be rotated to various positions by a userbetween data acquisitions, but they are not caused to be Rotating whiledata is being acquired, (Typical positioning of analyzer and polarizerazimuthal angles are plus or minus forty-five (+/−45) degrees).

Continuing, a present invention method of calibrating a spectroscopicellipsometer system comprising the steps of:

a. providing a spectroscopic ellipsometer system as described aboveherein, either independently or in functional combination with areflectometer system;

said method further comprising, in any functional order, the steps of:

b. for each of at least two ellipsometrically different sample systems,obtaining at least one multi-dimensional data set(s) comprisingintensity as a function of wavelength and a function of a plurality ofdiscrete settings of said at least one means for discretely,sequentially, modifying a polarization state of a beam ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation;

c. providing a mathematical model of the ellipsometer system, includingprovision for accounting for the settings of said at least one means fordiscretely, sequentially, modifying a polarization state of a beam ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation utilized in step b; and

d. by simultaneous mathematical regression onto said data sets,evaluating parameters in said mathematical model, including polarizationstate changing aspects of each of said plurality of discrete settings ofsaid at least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation.

It is also mentioned that said method of calibrating a spectroscopicellipsometer system can require, in the step b. obtaining of at leastone multi-dimensional data set(s) comprising intensity as a function ofwavelength and a function of a plurality of discrete settings of said atleast one means for discretely, sequentially, modifying a polarizationstate of a beam of electromagnetic radiation, the obtaining of data fromat least as many sample systems as are utilized discrete settings ofsaid at least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation. However, ifcharacteristics of a means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation areparameterized, say as a function of wavelength, are expressed byequations with a minimized number of parameters therein, it is possibleto reduce the number of sample systems which must be utilized.

The preferred embodiment of the present invention involves positioninginput and output polarizer/analyzer system azimuthal angles at typicalfixed, nominal, constant plus or minus forty-five (+/−45) degrees,although use of polarizer and analyzer elements which are rotatablebetween data acquisition procedures is acceptable. It is noted that thestatic positioning of said input and output polarizer/analyzer systemazimuthal angles greatly simplifies data acquisition, in that no phasesensors are required to detect rotational positioning are necessary,because synchronization is unnecessary. That is, as ellipsometric datais acquired asynchronously, the system requirements are greatly reducedas compared to ellipsometer systems which involve elements that arecaused to rotate during data acquisition. Also, as alluded to, fiberoptics are the preferred via for transporting electromagnetic radiationto and from the ellipsometer system portion of the present invention.The foregoing points make it possible to retro-fit mount theellipsometer portion of the present invention to existing spectroscopicreflectometer systems, (such as those presently marketed by NanometricsInc.), in a manner that optionally involves sharing of a source ofelectromagnetic radiation and/or detector system thereof with saidellipsometer system.

While the foregoing has disclosed the present invention system, itremains to describe the mathematical basis for practicing the presentinvention. As described, the present Discrete Polarization StateSpectroscopic Ellipsometer (DSP-SE_(tm)) system basically consists of asource of polychromatic electromagnetic radiation, an optical elementfor setting a polarization state, (eg. a polarizer), a stage forsupporting a sample system with a sample system present thereupon, ameans for discretely, sequentially, modifying a polarization state of abeam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization states by passage therethrough, an analyzer, and a meansfor detecting beam intensity, (eg. a detector system). As indicated, inpractice the input element is typically a polarizer with itstransmission axis oriented approximately +45 or −45 degrees from thesample system plane of incidence. Using Mueller Matrix/Stokes VectorCalculus, the input beam passing through such a polarizer is representedby:

$I_{P} = \begin{pmatrix}1 \\{\cos\left( {2P} \right)} \\{\sin\left( {2P} \right)} \\0\end{pmatrix}$where “P” is the azimuthal angle of the polarizer with respect to thesample plane of incidence. For optimal performance over a wide range ofsample systems, and computational simplicity, the “P” is usually chosento be +/−45 degrees, and the Stokes Vector becomes:

$I_{P} = \begin{pmatrix}1 \\0 \\{\pm 1} \\0\end{pmatrix}$

Now, an isotropic sample can be optically modeled by the Mueller Matrix:

$M_{S} = \begin{pmatrix}1 & {- N} & 0 & 0 \\{- N} & 1 & 0 & 0 \\0 & 0 & C & S \\0 & 0 & {- S} & C\end{pmatrix}$and the Stokes Vector resulting from a polarized polychromaticelectromagnetic radiation beam interaction with a sample system isdescribed by:

${M_{S} \cdot I_{P}} = {{\begin{pmatrix}1 & {- N} & 0 & 0 \\{- N} & 1 & 0 & 0 \\0 & 0 & C & S \\0 & 0 & {- S} & C\end{pmatrix} \cdot \begin{pmatrix}1 \\0 \\{\pm 1} \\0\end{pmatrix}} = \begin{pmatrix}1 \\{- N} \\{C \cdot {\pm 1}} \\{{- S} \cdot {\pm 1}}\end{pmatrix}}$

A generalized polarization state modifier (PSM) element, (which cancomrpise a combination of elements), followed by a polarization stateinsensitive detector yields the following Stokes Vector:

$\begin{matrix}{{PSM} = {\begin{pmatrix}1 & 0 & 0 & 0\end{pmatrix} \cdot \begin{pmatrix}{m00} & {m01} & {m02} & {m03} \\{m10} & {m11} & {m12} & {m13} \\{m20} & {m21} & {m22} & {m23} \\{m30} & {m31} & {m32} & {m33}\end{pmatrix}}} \\{= \begin{pmatrix}{m00} & {m01} & {m02} & {m03}\end{pmatrix}}\end{matrix}$therefore, if there are “n” discrete polarization states, the beamintensity measured for the “n'th” polarization state is:

$\begin{matrix}{I_{n} = {{{PSM}_{n} \cdot M_{S} \cdot I_{P}} = \left( \begin{matrix}{m0}_{n} & {m1}_{n} & {m2}_{n} & {\left. {m3}_{m} \right) \cdot}\end{matrix} \right.}} \\{\begin{pmatrix}1 & {- N} & 0 & 0 \\{- N} & 1 & 0 & 0 \\0 & 0 & C & S \\0 & 0 & {- S} & C\end{pmatrix} \cdot \begin{pmatrix}1 \\0 \\{\pm 1} \\0\end{pmatrix}} \\{= {{m0}_{n} - {{m1}_{n} \cdot N} + {\left( {{{m2}_{n} \cdot C} - {{m3}_{m} \cdot S}} \right) \cdot {\pm 1}}}}\end{matrix}$The transfer matrix for traditional 4-detector polarimeter systems isconstructed by inserting the (PSM) into “rows” which correspond to thepolarization state measured by each detector:

$I_{n} = {{{A \cdot S}\mspace{14mu}\begin{pmatrix}I_{0} \\I_{1} \\I_{2} \\I_{3}\end{pmatrix}} = {\begin{pmatrix}{m0}_{0} & {m1}_{0} & {m2}_{0} & {m3}_{0} \\{m0}_{1} & {m1}_{1} & {m2}_{1} & {m3}_{1} \\{m0}_{2} & {m1}_{2} & {m2}_{2} & {m3}_{2} \\{m0}_{3} & {m1}_{3} & {m2}_{3} & {m3}_{3}\end{pmatrix} \cdot \begin{pmatrix}1 \\{- N} \\{C \cdot {\pm 1}} \\{{- S} \cdot {\pm 1}}\end{pmatrix}}}$

If the “A” transfer matrix is invertable, (ie. the determinate isnon-zero), it can be concluded that sample system's N, C and Sellipsometric parameters can be determined from the measured intensitiesat each detector.

$\begin{pmatrix}1 \\{- N} \\{C \cdot {\pm 1}} \\{{- S} \cdot {\pm 1}}\end{pmatrix} = {A^{- 1} \cdot \;\begin{pmatrix}I_{0} \\I_{1} \\I_{2} \\I_{3}\end{pmatrix}}$Furthermore, in a traditional 4-detector polarimeter system, the “A”transfer matrix is determined, (at each wavelength of operation), byinputting a series of known polarization states and measuring theresulting intensities at each detector.

While the present invention (DSP-SE_(tm)) is similar to traditional4-detector polarimeter systems, if differs in that more than 4polarization states can optionally be incorporated into the measurement.The “A” matric therefore is generally not “square”, and a simpleinversion can not be used to directly extract sample system N, C and Sellipsometic parameters. Regression analysis based on known opticalmodels can also be used to determine, (ie. calibrate), the “A” transfermatrix of the system, and to extract the ellipsometric parameters fromthe “n” measuremed intensities.

While many variations are possible, in the preferred, non-limiting,embodiment of the present invention the (DSP-SE_(tm)) the inputpolarizer, as mentioned, is fixed at 45 degrees, such that the StokesVector which enters the polarimeter after interaction with the samplesystem is given by:

${M_{S} \cdot I_{P}} = {{k \cdot \begin{pmatrix}1 & {- N} & 0 & 0 \\{- N} & 1 & 0 & 0 \\0 & 0 & C & S \\0 & 0 & {- S} & C\end{pmatrix} \cdot \begin{pmatrix}1 \\0 \\1 \\0\end{pmatrix}} = {k \cdot \begin{pmatrix}1 \\{- N} \\C \\{- S}\end{pmatrix}}}$(where “k” is an arbitrary constant which accounts for the unknownintensity provided by the source of polychromatic electromagneticradiation).

For the 1st discrete polarization state of the detector system, apolarizer, (typically termed an analyzer when placed after the samplesystem), with the azimuthal angle threof set at 45 degrees, the detectedintensity is of the form:

$I_{0} = {{{PSM}_{0} \cdot M_{S} \cdot I_{P}} = {{\begin{pmatrix}1 & 0 & {- 1} & 0\end{pmatrix} \cdot k \cdot \begin{pmatrix}1 \\{- N} \\C \\{- S}\end{pmatrix}} = {k \cdot \left( {1 - C} \right)}}}$For the next two discrete polarization states, a quarter-wave retardercan be inserted in front of the analyzer, at azimuthal angles of zero(0.0) and ninety (90) degrees respectively, to provide:

$I_{1} = {{{PSM}_{1} \cdot M_{S} \cdot I_{P}} = {{\begin{pmatrix}1 & 0 & {- 1} & 0\end{pmatrix} \cdot \begin{pmatrix}1 & 0 & 0 & 0 \\0 & 1 & 0 & 0 \\0 & 0 & 0 & 1 \\0 & 0 & {- 1} & 0\end{pmatrix} \cdot k \cdot \begin{pmatrix}1 \\{- N} \\C \\{- S}\end{pmatrix}} = {k \cdot \left( {1 + S} \right)}}}$(for  retarder@0^(∘))$I_{2} = {{{PSM}_{2} \cdot M_{S} \cdot I_{P}} = {{\begin{pmatrix}1 & 0 & {- 1} & 0\end{pmatrix} \cdot \begin{pmatrix}1 & 0 & 0 & 0 \\0 & 1 & 0 & 0 \\0 & 0 & 0 & {- 1} \\0 & 0 & 1 & 0\end{pmatrix} \cdot k \cdot \begin{pmatrix}1 \\{- N} \\C \\{- S}\end{pmatrix}} = {k \cdot \left( {1 - S} \right)}}}$(for  retarder@90^(∘))For two additional discrete polarization states, a quarter-wave retardercan be inserted in front of the analyzer, at azimuthal angles of +/−twenty-two (22) degrees, respectively, to provide:

$I_{3} = {{{PSM}_{3} \cdot M_{S} \cdot I_{P}} = {{\begin{pmatrix}1 & \begin{matrix}0 & {- 1} & 0\end{matrix}\end{pmatrix} \cdot \begin{pmatrix}1 & 0 & 0 & 0 \\0 & \frac{1}{2} & \frac{1}{2} & {\frac{- 1}{2} \cdot \sqrt{2}} \\0 & \frac{1}{2} & \frac{1}{2} & {\frac{1}{2} \cdot \sqrt{2}} \\0 & {\frac{1}{2} \cdot \sqrt{2}} & {\frac{- 1}{2} \cdot \sqrt{2`}} & 0\end{pmatrix} \cdot k \cdot \begin{pmatrix}1 \\{- N} \\C \\{- S}\end{pmatrix}} = {\left( {1 - {\frac{1}{2} \cdot C} + {\frac{1}{2} \cdot N} + {\frac{1}{2} \cdot \sqrt{2} \cdot S}} \right) \cdot {k\left( {{for}\mspace{14mu}{{retarder}@{+ 22.5}}{^\circ}} \right)}}}}$

$\begin{matrix}{I_{1} = {{{PSM}_{4} \cdot M_{S} \cdot I_{P}} = {\left( {{1\mspace{14mu} 0} - {1\mspace{14mu} 0}} \right) \cdot}}} \\{\left( \begin{matrix}1 & 0 & 0 & 0 \\0 & \frac{1}{2} & \frac{- 1}{2} & {\frac{1}{2} \cdot \sqrt{2}} \\0 & \frac{- 1}{2} & \frac{1}{2} & {\frac{1}{2} \cdot \sqrt{2}} \\0 & {\frac{- 1}{2} \cdot \sqrt{2}} & {\frac{- 1}{2} \cdot \sqrt{2}} & 0\end{matrix} \right) \cdot k \cdot \left( \begin{matrix}1 \\{- N} \\C \\{- S}\end{matrix} \right)} \\{= {\left( {1 + {{\frac{1}{2} \cdot \sqrt{2 \cdot}}S} - {\frac{1}{2} \cdot N} - {\frac{1}{2} \cdot C}} \right) \cdot {k\left( {{for}\mspace{14mu}{{retarder}@{- 22}}\mspace{14mu} 5^{\prime}} \right)}}}\end{matrix}$

Simple combinations of these intensities yield:l ₀ =k(1−C)l ₁ −l ₂=2·k·Sl ₁ +l ₂=2·kl_(J) −l ₄ =k·Nfrom which sample system N, C, S, and are easily derived as:

$N = {2 \cdot \frac{I_{3} - I_{4}}{I_{1} + I_{2}}}$$C = \frac{\left( {I_{1} + I_{2} - {2 \cdot I_{0}}} \right)}{\left( {I_{1} + I_{2}} \right)}$$S = \frac{\left( {I_{1} - I_{2}} \right)}{\left( {I_{1} + I_{2}} \right)}$$\Delta = {a\;{\tan\left( \frac{S}{C} \right)}}$$\Psi = {{\frac{1}{2} \cdot a}\;{\tan\left( \frac{\sqrt{C^{2} + S^{2}}}{N} \right)}}$While the math for the preceeding 5-state (DSP-SE_(tm)) system iselegant, a potential difficulty in implementing said design is thatinsertion of the quarter-wave plates to effect polarization states 1–4,introduces intensity loss as a result of reflection from the opticalelement surface, which is not present when obtaining the first data setwherein no quarter-wave plate is present. This additional intensity lossmust be accounted for in the calibration algorithm. A modified approachinvolves not obtaining or not utilizing the first data set. While thisslightly complicates the equations, a simple analytic solution is stillpossible and values for N, C and S can be derrived as:l ₁ −l ₂=2·k·Sl ₁ +l ₂=2·kl _(J) −l ₄ =k·Nl _(J) +l ₄=(2−C+√{square root over (2)}·S)·k

$N = {2 \cdot \frac{I_{3} - I_{4}}{I_{1} + I_{2}}}$$C = \frac{{\left( {2 - \sqrt{2}} \right) \cdot I_{2}} + {\left( {2 + \sqrt{2}} \right) \cdot I_{1}} - {2 \cdot \left( {I_{3} + I_{4}} \right)}}{\left( {I_{1} + I_{2}} \right)}$$S = \frac{\left( {I_{1} - I_{2}} \right)}{\left( {I_{1} + I_{2}} \right)}$

A more general 4-state (DSP-SE_(tm)) approach utilizes an inputpolarizer, an output analyzer and four (4) retarder elements at variousazimuthal orientations. In this approach while the azimuthalorientations for the optical elements are nominally chosen to be thesame as in the preceeding design, arbitrary azimuthal orientations aswell as non-ninety degree retardation values are allowed. Under thisapproach, the Stokes Vector provided to the Polarimeter is given by:

$\begin{matrix}\begin{matrix}{I_{S,P} = {\left( \begin{matrix}1 & {- N} & 0 & 0 \\{- N} & 1 & 0 & 0 \\0 & 0 & C & S \\0 & 0 & {- S} & C\end{matrix} \right) \cdot \left( \begin{matrix}1 \\{\cos\left( {2P} \right)} \\{\sin\left( {2P} \right)} \\0\end{matrix} \right)}} \\{= {\left( \begin{matrix}{1 - {N \cdot {\cos\left( {2 \cdot P} \right)}}} \\{{- N} + {\cos\left( {2 \cdot P} \right)}} \\{C \cdot {\sin\left( {2 \cdot P} \right)}} \\{{- S} \cdot {\sin\left( {2 \cdot P} \right)}}\end{matrix} \right) = \left( \begin{matrix}{s0} \\{s1} \\{s2} \\{s3}\end{matrix} \right)}}\end{matrix} & \left( {{DPS}\mspace{14mu}\#\; 1} \right)\end{matrix}$(where “P” is the input polarimeter azimuth).The response of each discrete polarization state “n” to an input StokesVector is:

$\begin{matrix}{{I_{n} = \left( {{m0}_{n}\mspace{14mu}{m1}_{n}\mspace{14mu}{m2}_{n}\mspace{14mu}{m3}_{n}} \right)}\begin{matrix}{{m0}_{n} = 1} \\{{m1}_{n} = {{\left( {{{cr}_{n} \cdot {sr}_{n}} - {c\;{\delta_{n} \cdot {sr}_{n} \cdot {cr}_{n}}}} \right) \cdot {S2A}} + \left( {cr}_{n} \right)^{2} +}} \\{c\;{\delta_{n} \cdot \left( {sr}_{n} \right)^{2} \cdot {C2A}}} \\{{m2}_{n} = {{\left\lbrack {\left( {sr}_{n\;} \right)^{2} + {c\;{\delta_{n} \cdot \left( {cr}_{n} \right)^{2}}}} \right\rbrack \cdot {S2A}} + \left( {{{sr}_{n} \cdot {cr}_{n}} -} \right.}} \\{\left. {c\;{\delta_{n} \cdot {cr}_{n} \cdot {sr}_{n}}} \right) \cdot {C2A}} \\{{m3}_{n} = {{\left( {{{S2A} \cdot {cr}} - {{C2A} \cdot {sr}}} \right) \cdot s}\;\delta}}\end{matrix}{{{{where}\mspace{14mu}{cr}} = {\cos\left( {2r} \right)}},{{sr} = {\sin\left( {2r} \right)}},{{c\;\delta} = {\cos(\delta)}},{{s\;\delta} = {\sin(\delta)}},{{C2A} = {\cos\left( {2A} \right)}},{{S2A} = {\sin\left( {2A} \right)}},{r\mspace{14mu}{is}}}{{{the}\mspace{14mu}{retarder}\mspace{14mu}{azimuthal}\mspace{14mu}{orientation}\mspace{14mu}{angle}},{\delta\mspace{14mu}{is}}}{{{the}\mspace{14mu}{retardance}},{{and}\mspace{14mu} A\mspace{14mu}{is}\mspace{11mu}{the}\mspace{14mu}{analyzer}\mspace{14mu}{{orientation}.\left( {{{for}\mspace{14mu}{most}\mspace{14mu}{retarders}},{{the}\mspace{14mu}{retardance}\mspace{14mu}{varies}\mspace{14mu}{inversely}{with}\mspace{14mu}{wavelength}},{{{that}\mspace{14mu}{is}\mspace{14mu}{\delta(\lambda)}} = {\delta_{c}\text{/}\lambda}}} \right)}}}} & \left( {{DPS}\mspace{14mu}{\# 2}} \right)\end{matrix}$These polarization state modifying vectors can be packed into a (4×4)square transfer matrix “A”, such that the measured intensity for eachdiscrete state is given by:

$I_{n} = {{A \cdot {I_{S,P}\left( \begin{matrix}I_{0} \\I_{1} \\I_{2} \\I_{3}\end{matrix} \right)}} = {\left( \begin{matrix}{m0}_{0\;} & {m1}_{0} & {m2}_{0} & {m3}_{0} \\{m0}_{1} & {m1}_{1} & {m2}_{1} & {m3}_{1} \\{m0}_{2} & {m1}_{2} & {m2}_{2} & {m3}_{2} \\{m0}_{3} & {m1}_{3} & {m2}_{3} & {m3}_{3}\end{matrix} \right) \cdot \left( \begin{matrix}{s0} \\{s1} \\{s2} \\{s3}\end{matrix} \right)}}$To determine the Stokes Vector incident on the Polarimeter, the transfermatrix “A” s inverted and multiplied times the measured intensitiescoresponding to each discrete polarization state:

$\left( \begin{matrix}{s0} \\{s1} \\{s2} \\{s3}\end{matrix} \right) = {\left( \begin{matrix}{m0}_{0\;} & {m1}_{0} & {m2}_{0} & {m3}_{0} \\{m0}_{1} & {m1}_{1} & {m2}_{1} & {m3}_{1} \\{m0}_{2} & {m1}_{2} & {m2}_{2} & {m3}_{2} \\{m0}_{3} & {m1}_{3} & {m2}_{3} & {m3}_{3}\end{matrix} \right)^{- 1} \cdot \left( \begin{matrix}I_{0} \\I_{1} \\I_{2} \\I_{3}\end{matrix} \right)}$and the sample system parameters:N=cos(2·P)−s1

$C = \frac{s2}{\sin\left( {2 \cdot P} \right)}$

$S = \frac{- {s3}}{\sin\left( {2 \cdot P} \right)}$can then be extracted. To illustrate this approach, a transfer matrix isconstructed assuming nominal azimuthal orientations of (0.0), (90)(+22.5) and (−22.5) degrees for each of the four (4) discretepolarization states. The same nominal retardance is assumed for eachretarder. The analytical inversion of this matrix is very complicated,but it is still trivial to numerically invert the matrix given thesample expressions for each element given by:

$A = \left( \begin{matrix}1 & {C2A} & {c\;{\delta \cdot {S2A}}} & {{{S2A} \cdot s}\;\delta} \\1 & {C2A} & {c\;{\delta \cdot {S2A}}} & {- \left( {{{S2A} \cdot s}\;\delta} \right)} \\1 & {{\left( {1 - {c\;\delta}} \right) \cdot \frac{S2A}{2}} + {\left( {1 + {c\;\delta}} \right) \cdot \frac{C2A}{2}}} & {{\left( {1 + {c\;\delta}} \right) \cdot \frac{S2A}{2}} + {\left( {1 - {c\;\delta}} \right) \cdot \frac{C2A}{2}}} & {{\left( {{S2A} - {C2A}} \right) \cdot s}\;{\delta \cdot \frac{\sqrt{2}}{2}}} \\1 & {{{- \left( {1 - {c\;\delta}} \right)} \cdot \frac{S2A}{2}} + {\left( {1 + {c\;\delta}} \right) \cdot \frac{C2A}{2}}} & {{\left( {1 + {c\;\delta}} \right) \cdot \frac{S2A}{2}} - {\left( {1 - {c\;\delta}} \right) \cdot \frac{C2A}{2}}} & {{\left( {{S2A} + {C2A}} \right) \cdot s}\;{\delta \cdot \frac{\sqrt{2}}{2}}}\end{matrix} \right)$Multiplying the inverted matrix by the measured intensities for eachdiscrete polarization state allows straight forward determination of thesample system characterizing N, C, S, Ψ, and Δ.A General Regression Based Approach to Calibration of (DSP-SE_(tm))systems and allow extraction of accurate ellipsometric sample systemcharacterizing data assumes that the (DSP-SE_(tm)) system measurespolychromatic electromagnetic radiation beam intensity at “n” discretepolarization states, and that “m” samples with different ellipsometricproperties are utilized. For a traditional polarimeter system, which iscalibrated on a wavelength by wavelength basis, it is necessary to have“m” be greater than or equal to “n”. However, utilizing globalregression which allows calibration parameters to be parameterized vs.wavelength, (thereby reducing the number of parameters required todescribe the system transfer Matrices “A” at each wavelength), it ispossible to reduce the number of calibration sample systems required,“m”, to be less than “n”. Under this approach, calibration of a presentinvention (DSP-SE_(tm)) system, a multi-dimensional data set “I” ismeasured consisting of measured polychromatic electromagnetic radiationbeam intensities for each discrete polarization state, on eachcalibration sample system, and at each wavelength in the spectral rangeof the instrument:

${{Igen}\left( p_{y} \right)}_{i,j,k} = {A \cdot \left( \begin{matrix}1 & {- N_{j,k}} & 0 & 0 \\{- N_{j,k}} & 1 & 0 & 0 \\0 & 0 & C_{j,k} & S_{j,k} \\0 & 0 & {- S_{j,k}} & C_{j,k}\end{matrix} \right) \cdot \left( \begin{matrix}{s0} \\{s1} \\{s2} \\{s3}\end{matrix} \right)}$

To generate “predicted” intensities measured by the (DSP-SE_(tm)), (as afunction of calibration parameters spsecified in the vector p_(y)), thefollowing equation is applied:lexp_(i,j,k)where

-   -   i=1 . . . n (for each discrete polarization state)    -   j=1 . . . m (for each calibration sample)    -   k=1 . . . w (for each wavelength)        where “A” is an (“n”×4) matrix, in which each row is possibly        parameterized by foregoing equation DSP#2 and the input vector        s_(n) is possibly parameterized by the input polarizer azimuth        by an equation DSP#1. The extraction of calibration sample        system's N, C and S parametres can be calculated as a function        of film thickness and angle of incidence (given calibration        sample systems which are well characterized by known optical        models and optical constants, such as SiO₂ on Si films with        systematically increasing SiO₂ film thicknesses).

To perform regression analysis, the “chi-squared” function:

$x^{2} = {\sum\limits_{i = 1}^{n}\;{\sum\limits_{j = 1}^{m}\;{\sum\limits_{k = 1}^{w}\;\left\lbrack {\frac{I\;\exp_{i,j,k}}{\sqrt{\sum\limits_{i = 1}^{m}\;\left( {I\;\exp_{i,j,k}} \right)^{2}}} - \frac{{{Igen}\left( p_{y} \right)}_{i,j,k}}{\sqrt{\sum\limits_{i = 1}^{m}\;\left( {I\;{\exp\left( p_{y} \right)}_{i,j,k}} \right)^{2}}}} \right\rbrack^{2}}}}$is then minimized, (typically utilizing a non-linear regressionalgorithm such as “Marquard-Levenberg”), by adjusting calibrationparameters specified in the vector “p_(y)”. To aid in the regression,both the experimental and generated intensity vectors are normalized bythe sum of the squares of all the discrete polarization states at eachwavelength.

If the global parameterization of calibration parameters is not used,then the vector “p_(y)” consists of the input Stokes Vector values“s_(n)”, and the elements of the transfer matrix “A”, all of which mustbe defined at each wavelength, This requires at least (4+(4×n))×w)calibration parameters, assuming that the ellipsometric parameters (N, Cand S), for each calibration sample system are exactly known.

Further, if global parameterization is used, the input vector “s_(n)”for all wavelengths can be parameterized by the input polarizer azimuth“p” the ellipsometric parameters of the “m” calibration samples can beparametrically calculated as function of angle of incidence (φ_(m)) andfilm thickness “t_(m)” and the transfer matrix “A” can be parameterizedby the Azimuth of the analyzer “A”, the orientation of each retarder“r_(n)”, and the retardance of each retarder as a function of wavelength

S(λ)_(n)±δc_(n)/λ. It is noted that higher order terms could also beadded to the retardance vs. wavelength function, or to any other of thecalibration parameters to improve fit between the experimentallymeasured and modeled generated data. Such a global parameterizationsignificantly reduces the number of calibration parameters required todescribe the (DSP-SE_(tm)) system over a spectroscopic range ofwavelengths. The total number of calibration parameters in thissuggested parameterization (other variations are certainly possible aswell), may be as few as:p _(y) =P+φ _(m) +t _(m) +A+r _(n) +δc _(m)=1+m+m+1+n+m=(2×m)+(2×n)+2.To extract the ellipsometric parameters of an arbitrary sample systemwhich is inserted into a general (DSP-SE_(tm)) system, a regressionanalysis can also be performed, and N, C and S can be defined andevaluated by regression at each wavelength separately.

Further, if the plane of incidence of the sample system is allowed tovary slightly, (to account for imperfect alignment to the ellipsometersystem), the Stokes Vector which enters the discrete polarization statemodifier becomes:

$\begin{matrix}{{M_{s} \cdot I_{p}} = {k \cdot \left( \begin{matrix}1 & 0 & 0 & 0 \\0 & {\cos(s)} & {- {\sin(s)}} & 0 \\0 & {\sin(s)} & {\cos(s)} & 0 \\0 & 0 & 0 & 1\end{matrix} \right) \cdot \left( \begin{matrix}1 & {- N} & 0 & 0 \\{- N} & 1 & 0 & 0 \\0 & 0 & C & S \\0 & 0 & {- S} & C\end{matrix} \right) \cdot}} \\{{\left( \begin{matrix}1 & 0 & 0 & 0 \\0 & {\cos(s)} & {\sin(s)} & 0 \\0 & {- {\sin(s)}} & {\cos(s)} & 0 \\0 & 0 & 0 & 1\end{matrix} \right) \cdot \left( \begin{matrix}1 \\0 \\1 \\0\end{matrix} \right)} = {k \cdot \left\lbrack \begin{matrix}{1 - {s \cdot N}} \\{{- N} + {s \cdot \left( {1 - C} \right)}} \\{{{- s} \cdot N} + C} \\{- S}\end{matrix} \right\rbrack}}\end{matrix}$where “s” is the azimuthal misalignment of the sample system, andpresumably is very near zero.In this case the (DSP-SE_(tm)) system, would not measure the “true” N, Cand S parameters, but would instead measure “effective” parameters Neff,Ceff and Seff:Neff=N−s·(1−C)Ceff=C=s·NSeff=SIt would be possible to include the azimuthal misalignment factor “s” asa fitting parameter in subsequent analysis of the ellipsometric datameasured by a (DSP-SE_(tm)) system.

It is believed that the present invention spectroscopic ellipsometersystem combination comprising:

-   -   Polarizer and analyzer, (which are both fixed in position during        data acquisition); and    -   at least one stepwise rotatable compensator means for        discretely, sequentially, modifying a polarization state of a        beam of electromagnetic radiation provided by said source of        polychromatic electromagnetic radiation through a plurality of        polarization states, said means being present at at least one        location selected from the group consisting of:        -   between said polarizer and said stage for supporting a            sample system; and        -   between said stage for supporting a sample system and said            analyzer;            said at least one stepwise rotatable compensator means for            discretely, sequentially, modifying a polarization state of            a beam of electromagnetic radiation provided by said source            of polychromatic electromagnetic radiation through a            plurality of polarization states, being positioned so that            said beam of electromagnetic radiation transmits            therethrough in use;            is Patentably distinct over all prior art other than Patents            which are co-owned by the J.A. Woollam Co. Inc.            Patentability is thought to be further enhanced when said            present invention spectroscopic ellipsometer system is            combined with a reflectometer system, (particularly when            said present invention spectroscopic ellipsometer system and            reflectometers system share a common source of            electromagnetic radiation and/or a multi-element            spectroscopic detector thereof),            and/or            where the source of polychromatic radiation comprises a            system for providing an output beam of polychromatic            electromagnetic radiation, which has a relatively broad and            flattened intensity vs. wavelength characteristic over a            wavelength spectrum, which comprises at least a first and a            second source of polychromatic electromagnetic radiation;            and at least a first electromagnetic beam combining means            comprising a plate, (eg. uncoated fused silica or glass etc.            such that reflection/transmission characteristics thereof            are determined by angle-of-incidence and polarization state            of a beam of electromagnetic radiation).

The present invention will be better understood by reference to theDetailed Description Section of this Specification, in combination withthe Drawings.

SUMMARY

It is therefore a primary purpose and/or objective of the presentinvention to disclose spectroscopic ellipsometer and combinedspectroscopic reflectometer/ellipsometer systems, as well as methods ofcalibration therefore; which present invention system includes, in thespectroscopic ellipsometer portion thereof, provision of polarizer andanalyzer elements which are fixed in position during data acquisitionprocedures, and at least one stepwise rotatable compensator means forimposing a plurality of sequentially discrete, rather than continuouslyvarying, polarization states onto a beam of electromagnetic radiationcaused to be present in said spectroscopic ellipsometer system.

It is another purpose and/or objective yet of the present invention todisclose a preferred, but not limiting, source of electromagneticradiation which provides a plurality of wavelengths combined from aplurality of sources.

It is another purpose and/or objective of the present invention todisclose a method of calibration of the spectroscopic ellipsometersystem portion of the present invention system which utilizes dataobtained utilizing a sequential plurality of polarization states.

Other purposes and/or objectives will become clear from a reading of theSpecification and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a present invention spectroscopic ellipsometer systemconfiguration.

FIG. 2 shows a combined present invention spectroscopicreflectometer/ellipsometer system.

FIG. 3 a shows a frontal perspective view of a discrete state polarizercomprising a wheel with five discrete polarizer elements mountedthereupon.

FIG. 3 b shows a side elevational view of a discrete state polarizer, asin FIG. 3 a, oriented so that an electromagnetic beam passing throughone of the discrete polarizer five elements.

FIG. 3 c shows a front elevational view of a discrete state polarizerwith five laterally slideably mounted discrete polarizer elementsmounted therein.

FIG. 3 d shows a present invention system for providing an output beam(OB) or (OB′) of polychromatic electromagnetic radiation which has arelatively broad and flattened intensity vs. wavelength characteristicover a wavelength spectrum.

FIGS. 3 e–3 i demonstrate functional construction of preferred presentinvention compensator systems.

FIGS. 3 j 1–3 p show additional functional construction of compensatorsystems which are within the scope of the present invention.

FIG. 4 demonstrates the flow of a present invention method ofcalibration of the spectroscopic ellipsometer portion of the presentinvention.

FIGS. 5–11 show Intensity vs. Wavelength for the seven (7)ellipsometrically different samples, obtained by fitting a mathematicalmodel of the samples and the spectroscopic ellipsometer system byregression onto experimentally obtained data obtained at each of five(5) discrete polarization states.

FIGS. 12 & 13 show PSI and DELTA values obtained for samples with thinand thick layers of Oxide thereupon.

FIGS. 14–16 provide insight to the Psuedo-Achromatic characteristicsachieved by a FIG. 3 f Compensator design.

DETAILED DESCRIPTION

FIGS. 1–3 d and 4–13 show material previously disclosed in Co-Pendingapplication Ser. No. 09/517,125, and discussion thereof is repeatedherein to provide full disclosure and background for introducingmaterial which is new herewithin. FIGS. 3 e–3P demonstrate Compensatorsfor application in the present invention, and FIGS. 14–16 showRetardation vs. Wavelength for Compensator designs which arePseudo-Achromatic.

Turning now to FIG. 1, there is shown a spectroscopic ellipsometersystem configuration. Shown are a source of polychromaticelectromagnetic radiation (QTH), (eg. a quartz-halogen-lamp), apolarizer (P) a stage for supporting a sample system (STG) with a samplesystem (SS) present thereupon, a means (DSP) for discretely,sequentially, modifying a polarization state of a beam ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization states bypassage therethrough, an analyzer (A), and a detector system (DET).(Note preferred detector systems are spectroscopic multi-element such asBucket Brigade, Diode and CCD arrays and that “off-the-shelf”spectrometer systems such as manufactured by Zeiss can also be applied).Shown also are ellipsometer electromagnetic beam in (EBI) andellipsometer electromagnetic beam out (EBO). It is noted that said means(DSP) for discretely, sequentially, modifying a polarization state of abeam of electromagnetic radiation, while shown as present between saidstage (STG) for supporting a sample system (SS) and said analyzer (A),can generally be present as (DSP′) between said polarizer (P) and saidstage (STG) for supporting a sample system (SS), and/or as (DSP) betweensaid stage (STG) for supporting a sample system and said analyzer (A).

FIG. 2 shows a combined spectroscopic reflectometer/ellipsometer systemwherein the source of polychromatic electromagnetic radiation (QTH), anddetector (DET) system are common to both, and wherein the spectroscopicellipsometer system is shown as being provided input and outputelectromagnetic beam access via fiber optics (F1) and (F2). Shown arenear-normal orientation reflectometer electromagnetic beam in (RBI) andreflectometer electromagnetic beam out (RBO), as well as sample system(SS) specific near Brewster condition ellipsometer electromagnetic beamin (EBI) and ellipsometer electromagnetic beam out (EBO). While notshown, it is noted that the source of polychromatic electromagneticradiation (QTH), and detector (DET) system can be located distal fromboth the reflectometer and ellipsometer portions of the combinedspectroscopic reflectometer/ellipsometer system, with fiber optics beingpresent to interface to the reflectometer portion as well.

In both FIGS. 1 and 2, there can optionally be other (eg. focusingelements ((FE) (FE′)), present on one or both sides of the sample system(SS), as shown in dashed lines. Said other elements appearellipsometrically indistinguishable with polarization state modifiersduring use. Also shown in FIGS. 1 & 2 are Compensator Stepping Means(CSM) (CSM′) for use in stepwise rotating compensator (DSP) and/or(DSP′) or operating means as shown in FIGS. 3 a–3 c.

FIG. 3 a shows a frontal perspective view of a discrete state polarizer(DSP) comprising an essentially circular “wheel” element (WE) with fivediscrete polarization state modifiers elements (A) (B) (C) (D) and (E)mounted thereupon on the perimeter thereof, such that said andprojecting discrete polarization state modifier elements (A) (B) (C) (D)and (E) project perpendicularly to a surface thereof.

FIG. 3 b shows a side elevational view of a discrete state polarizer, asin FIG. 3 a, oriented so that an electromagnetic beam (EM) passingthrough one (C) of the five discrete polarization state modifiers (A)(B) (C) (D) and (E) elements. Note that discrete polarizer elements (A)and (B) are located behind discrete polarizer elements (E) and (D)respectively. Also note that if the essentially circular “wheel” element(WE) is caused to rotate about the pivot rod (PR) which projects from alower surface of said essentially circular “wheel” element, each of thevarious five discrete polarizer (A) (B) (C) (D) and (E) elements can berotated into the position in which is shown discrete polarizer element(C).

FIG. 3 c shows a front elevational view of a discrete state polarizerwith five laterally slideably mounted discrete polarizer (A) (B) (C) (D)and (E) elements mounted on a slider element (SE) which is mounted in aguide providing element (GE) therein. Sliding the slider element (SE) tothe right or left serves to position each of the five discrete polarizer(A) (B) (C) (D) and (E) elements in a position at which anelectromagnetic beam of radiation can be caused to be present. (Notemore or less than five discrete polarizer elements can be present).

The embodiments in FIGS. 3 a–3 c have been found to be difficult topractice, however, and it has been determined that a beter appraoch isto utilize rotatable compensator means to provide the discretepolarization state changes. FIGS. 3 e, 3 f, 3 g, 3 h and 3 i demonstratethat at least one Compensator can be applied as (DSP) or (DSP′) in FIGS.1 and 2, which at least one Compensator (DSP) and/or (DSP′), is, in use,rotated about the locus of the electromagnetic beam (EBI) or (EBO), byCompensator Rotation Stepping Means (CSM′) and/or (CSM). That is, thepresently disclosed invention then comprises a Discrete PolarizationState Spectroscopic Ellipsometer System, with the clarification beingthat the Discrete Polarization State effecting means (DSP) and/or (DSP′)is preferably a Rotatable Compensator, which during use is steppedthrough a plurality of discrete rotation angles, and then heldmotionless during data acquisition. While not limiting, a utilityproviding specific embodiment applies Psuedo-Achromatic RotatableCompensators. (Note, FIGS. 14–16 show various Psuedo-AchromaticRetardation vs. Wavelength characteristics possible utilizing multipleelement compensators, as shown in FIG. 3 f).

Further, essentially any Compensator which can be placed into a beam ofelectromagnetic radiation can be applied, such as those disclosed inclaim 9 of U.S. Pat. No. 5,872,630, (which 630 Patent is incorporated byreference hereinto):

Berek-type;

Non-Berek-type;

Zero Order;

Zero Order comprising a plurality of plates;

Rhomb;

Polymer;

Achromatic Crystal; and

Psuedo-Achromatic.

FIGS. 3 e, 3 f, 3 g, 3 h and 3 i demonstrate functional construction ofpreferred present invention compensator systems. FIG. 3 e simplyexemplifies that a single plate (SPC) compensator (1) can be applied.FIG. 3 f demonstrates construction of a compensator (2) from first (ZO1)and second (ZO2) effectively Zero-Order, (eg. Quartz or BicrystalineCadnium Sulfide or Bicrystaline Cadnium Selenide), Waveplates, each ofwhich effective Zero-Order Waveplates (ZO1) & (ZO2) is shown to beconstructed from two Multiple Order waveplates, (ie. (MOA1) & (MOB1) and(MOA2) & (MOB2), respectively). The fast axes (FAA2) & (FAB2) of saidsecond effective Zero-Order Waveplate (ZO2) are oriented away from zeroor ninety degrees, (eg. in a range around a nominal forty-five degreessuch as between forty and fifty degrees), with respect to the fast axes(FAA1) & (FAB1) of said first effective Zero-Order Waveplate (ZO1). Inparticular FIG. 14 b is a cross-sectional side view of a presentinvention preferred compensator (PC) constructed from a first effectivezero-order plate (ZO1) which is constructed from two multiple orderplates (MOA1) and (MOB1), and a second effective zero-order plate (ZO2)which is constructed from two multiple order plates (MOA2) and (MOB2).An entered electromagnetic beam (EMBI) emerges as electromagnetic beam(EMBO) with a retardation entered between orthogonal components thereofwith a Retardation vs. Wavelength. FIGS. 3 g and 3 h are views lookinginto the left and right ends of the preferred present inventionCompensator (PC) as shown in FIG. 3 f, and show that the Fast Axes(FAA2) and (FAB2) of the second effective Zero-Order Waveplate (ZO2) arerotated away from zero or ninety degrees and are ideally oriented atforty-five degrees, with respect to the Fast Axes (FAA1) & (FAB2) of thefirst effective Zero-Order Waveplate (ZO1). (Note that the fast axis(FAA1) of the first effective Zero-Order Waveplate (ZO1) is shown as adashed line in FIG. 3 h, for reference). FIG. 3 i demonstratesfunctional construction of another preferred compensator (2′) which isconstructed from two per se. single plate Zero-Order Waveplates (MOA)and (MOB), which are typically made of materials such as mica orpolymer.

(It is specifically to be understood that a present inventioncompensator system can be comprised of at least one Zero-Order waveplateand at least one effectively Zero-Order waveplate in combination, aswell as combinations comprised of two actual Zero-Order waveplates ortwo effectively Zero-Order waveplates).

FIGS. 3 j 1–3 p demonstrate additional compensators which can be appliedin the present invention.

FIG. 3 j 1 shows that the first additional present invention retardersystem (3) comprises a first triangular shaped element (P1), which asviewed in side elevation presents with first (OS1) and second (OS2)sides which project to the left and right and downward from an upperpoint (UP1). Said first triangular shaped element (P1) first (OS1) andsecond (OS2) sides have reflective outer surfaces. Said retarder system(3) further comprises a second triangular shaped element (P2) which asviewed in side elevation presents with first (IS1) and second (IS2)sides which project to the left and right and downward from an upperpoint (UP2), said second triangular shaped element (P2) being made ofmaterial which provides internally reflective, phase delay introducing,interfaces on first (IS1) and second (IS2) sides inside thereof. Saidsecond triangular shaped element (P2) is oriented with respect to thefirst triangular shaped element (P1) such that the upper point (UP2) ofsaid second triangular shaped element (P2) is oriented essentiallyvertically directly above the upper point (UP1) of said first triangularshaped element (P1). In use an input electromagnetic beam of radiation(LB) caused to approach said first (OS1) side of said first triangularshaped element (P1) along an essentially horizontally oriented locus, isshown as being caused to externally reflect from an outer surfacethereof and travel along as electromagnetic beam of radiation (R1) whichis essentially upwardly vertically oriented. Next said electromagneticbeam of radiation (R1) is caused to enter said second triangular shapedelement (P2) and essentially totally internally reflect from said first(IS1) side thereof, then proceed along an essentially horizontal locusand essentially totally internally reflect from the second (IS2) sidethereof and proceed along an essentially downward vertically orientedelectromagnetic beam of radiation (R3). This is followed by an externalreflection from an outer surface of said second side (OS2) of said firsttriangular shaped element (P1) such that said electromagnetic beam (LB′)of radiation proceeds along an essentially horizontally oriented locus,undeviated and undisplaced from the essentially horizontally orientedlocus of said input beam (LB) of essentially horizontally orientedelectromagnetic radiation. This is the case even when said retardersystem (3) is caused to rotate. The result of said described retardersystem (3) application being that retardation is entered betweenorthogonal components of said input electromagnetic beam of radiation(LB). Further, said first (P1) and second (P2) triangular shapedelements are typically right triangles in side elevation as shown inFIG. 3 j 1, and the outer surfaces of first (OS1) and second (OS2) sidesare typically, but not necessarily, made reflective by the presence of acoating of metal thereupon. A coating of metal serves assure a highreflectance and good electromagnetic beam radiation intensitythroughput. Also, assuming accurately manufactured right angle first(P1) and second (P2) triangular shaped elements are utilized, thiscompensator design provides inherent compensation of both angular andtranslational misalignments of the input light beam (LB). As well, thetotal retardence provided is compensated for angular misalignments ofthe input electromagnetic radiation beam. That is, if the inputelectromagnetic radiation beam (LB) is not aligned so as to form anangle of incidence of forty-five (45) degrees with the first outersurface (OS1), the reflected electromagnetic beam (R1) will internallyreflect at the first internal surface (IS1) of the second triangularshaped element (P2) at a larger (smaller) angle than would be the caseif said angle of incidence were forty-five (45) degrees. This effect,however, is directly compensated by a smaller (larger) angle ofincidence of electromagnetic beam (R2) where it internally reflects frominner surface (IS2) of the second triangular shaped element (P2). Asanother comment it is to be understood that because of the obliqueangles of incidence of the reflections from the outer surfaces (OS1) and(OS2) of the first triangular shaped element (P1) apolarimeter/ellipsometer in which said compensator (3) is present willrequire calibration to characterize the PSI-like component thereof.

FIG. 3 j 2 shows a variation (3′) on FIG. 3 j 1, wherein the firsttriangular shaped element is replaced by two rotatable reflecting means,identified as (OS1′) and (OS2′). This modification allows useradjustment so that the locus of an entering electromagentic beam (LB′)exits undeviated and undisplaced from an entering electromagentic beam(LB).

FIG. 3 k shows that the second additional present invention retardersystem (4) comprises a parallelogram shaped element which, as viewed inside elevation, has top (TS) and bottom sides (BS), each of length (d)parallel to one another, both said top (TS) and bottom (NS) sides beingoriented essentially horizontally. Said retarder system (4) also hasright (RS) and left (LS) sides parallel to one another, both said right(RS) and left (LS) sides being of length (d/cos(α)), where alpha (α) isshown as an angle at which said right (RS) and left (LS) sides projectfrom horizontal. Said retarder system (4) is made of a material with anindex of refraction greater than that of a surrounding ambient. In usean input beam of electromagnetic radiation (LB) caused to enter the leftside (LS) of said retarder system (4), along an essentially horizontallyoriented locus, is caused to diffracted inside said retarder system (4)and follow a locus which causes it to essentially totally internallyreflect from internal interfaces of both said top (TS) and bottom (BS)sides, and emerge from said retarder system (4) as (LB′) from the rightside (RS) thereof, along an essentially horizontally oriented locuswhich is undeviated and undisplaced from the essentially horizontallyoriented locus of said input beam (LB) of essentially horizontallyoriented electromagnetic radiation. This is the case even when saidretarder system (4) is caused to rotate. The result of said describedretarder system (4) application being that retardation is enteredbetween orthogonal components of said input electromagnetic beam orradiation at said internal reflections from the top (TS) and bottom (BS)surfaces. This retarder system is very robust as it is made of singlepiece construction. It is noted that adjustment of the angle alpha (α)in manufacture allows setting the amount of retardation which isprovided by the retarder system (4). In addition, coatings can beexternally applied to top (TS) and bottom surface (BS) to adjustretardation effected by internal reflection from said top (TS) andbottom (BS) surfaces. A formula which defines the retardation providedthereby being:

${\frac{d}{h} = {2 - {\tan(\phi)}}},{{{where}\mspace{14mu}\phi} = {\alpha \cdot {\sin^{- 1}\left( \frac{\sin\left( {90 - \alpha} \right)}{n} \right)}}}$

FIG. 31 shows that the third additional present invention retardersystem (5) comprises first (P1) and second (P2) triangular shapedelements. Said first (P1) triangular shaped element, as viewed in sideelevation, presents with first (LS1) and second (RS1) sides whichproject to the left and right and downward from an upper point (UP1),said first triangular shaped element (P1) further comprising a thirdside (H1) which is oriented essentially horizontally and which iscontinuous with, and present below said first (LS1) and second (RS1)sides. Said second triangular shaped element (P2), as viewed in sideelevation, presents with first (LS2) and second (RS2) sides whichproject to the left and right and upward from a lower point (LP2), saidsecond triangular shaped element (P2) further comprising a third side(H2) which is oriented essentially horizontally and which is continuouswith, and present above said first (LS2) and second (RS2) sides. Saidfirst (P1) and second (P2) triangular shaped elements being positionedso that a rightmost side (RS1) of said first (P1) triangular shapedelement is in contact with a leftmost side (LS2) of said second (P2)triangular shaped element over at least a portion of the lengthsthereof. Said first (P1) and second (P2) triangular shaped elements areeach made of material with an index of refraction greater than that of asurrounding ambient. In use an input beam (LB) of electromagneticradiation caused to enter the left (LS1) side of said first (P1)triangular shaped element and is caused to diffracted inside saidretarder system (5) and follow a locus which causes it to essentiallytotally internally reflect from internal interfaces of said third sides(H1) and (H2) of said first (P1) and second (P2) triangular shapedelements, respectively, and emerge from said right side (RS2) of saidsecond (P2) triangular shaped element as electromagnetic radiation beam(LB′) which is oriented along an essentially horizontal locus which isundeviated and undisplaced from the essentially horizontally orientedlocus of said input beam (LB) of essentially horizontally orientedelectromagnetic radiation. This is the case even when said retardersystem (5) is caused to rotate. The result of said described retardersystem (5) application being that retardation is entered betweenorthogonal components of said input electromagnetic beam of radiation(LB). It is noted that as long as the third sides (H1) and (H2) of saidfirst (P1) and second (P2) triangular shaped elements are parallel, theoutput electromagnetic beam (LB′) is undeviated and undisplaced from theinput electromagnetic beam (LB) in use. It is noted that The triangularshape elements (P1) and/or (P2) can be made of various materials withvarious indicies of refraction, and coating(s) can be applied to one orboth of the third sides (H1) and (H2) of said first (P1) and second (P2)triangular shaped elements to adjust retardation entered to anelectromagnetic beam (LB1).

FIG. 3 m shows that the forth additional present invention retardersystem (6) comprises a triangular shaped element, which as viewed inside elevation presents with first (LS) and second (RS) sides whichproject to the left and right and downward from an upper point (UP).Said retarder system (6) further comprises a third side (H) which isoriented essentially horizontally and which is continuous with, andpresent below said first (LS) and second (RS) sides. Said retardersystem (6) is made of a material with an index of refraction greaterthan that of a surrounding ambient. In use an input beam ofelectromagnetic radiation (LB) caused to enter the first (LS) side ofsaid retarder system (6) along an essentially horizontally orientedlocus, is caused to diffracted inside said retarder system (6) andfollow a locus which causes it to essentially totally internally reflectfrom internal interface of said third (H) side, and emerge from saidretarder system (6) from the second (RS) side along an essentiallyhorizontally oriented locus which is undeviated and undisplaced from theessentially horizontally oriented locus of said input beam ofessentially horizontally oriented electromagnetic radiation (LB). Thisis the case even when said retarder system (6) is caused to rotate. Theresult of said described retarder system (6) application being thatretardation is entered between orthogonal components of said inputelectromagnetic beam of radiation (LB). The FIG. 3 m retarder system (6)is typically an isosceles prism which is available off-the-shelf with anangle alpha (α) of forty-five (45) degrees. As long as the inputelectromagnetic beam (LB) height (h) is chosen in accordance with theformula:

${d = {2{h\left( {\frac{1}{\tan(\alpha)} + {\tan(\phi)}} \right)}}},{{{where}\mspace{14mu}\phi} = {\alpha + {\sin^{- 1}\left( \frac{\sin\left( {90 - \alpha} \right)}{n} \right)}}}$in conjunction with the index of refraction (n) of the material fromwhich the retarder system (6) is made, and the locus of the inputelectromagnetic radiation beam (LB) is parallel with the third side (H)of said retarder system (6), the output electromagnetic beam (LB′) willnot be deviated or translated with respect to the input electromagneticbeam (LB). As well, note the dashed line (DL) below the upper point(UP). This indicates that as the region above said dashed line (DL) isnot utilized, the portion of said retarder system (6) thereabove can beremoved. It is also noted that the input electromagnetic beam (LB)enters and exits the retarder system (6) other than along a normal to asurface thereof, said retarder system is not an ideal retarder with aPSI of forty-five (45) degrees. It is noted that the third side (H) ofthe retarder system (6) can be coated to change the retardation effectsof an internal reflection of an electromagnetic beam of radiationtherefrom, and such a coating can have an adverse effect on the nonidealPSI characteristics.

FIG. 3 p shows that the fifth additional present invention retardersystem (7) comprises first (PA1) and second (PA2) parallelogram shapedelements which, as viewed in side elevation, each have top (TS1)/(TS2)and bottom (BS1)/(BS2) sides parallel to one another, both said top(TS1) (TS2) and bottom (BS1) (BS2) sides each being oriented at an angleto horizontal. Said first (PA1) and second (PA2) parallelogram shapedelements also each have right (RS1)/(RS2) and left (LS1)/(LS2) sidesparallel to one another, all said right (RS1) (RS2) and left (LS1) (LS2)sides being oriented essentially vertically. Said first (PA1) and second(PA2) parallelogram shaped elements are made of material with an indexof refraction greater than that of a surrounding ambient. A right mostvertically oriented side (RS1) of said first parallelogram is in contactwith a leftmost (LS2) vertically oriented side of the secondparallelogram shaped element (PA2). In use an input beam ofelectromagnetic radiation (LB) caused to enter an essentially verticallyoriented left side LS1) of said first parallelogram shaped element (PA1)along an essentially horizontally oriented locus, is caused todiffracted inside said retarder system and follow a locus which causesit to essentially totally internally reflect from internal interfaces ofboth said top (TS1) (TS2) and bottom (BS1) (BS2) sides of both saidfirst and second parallelogram shaped elements (PA1) (PA2), then emergefrom a right side (RS2) of said second parallelogram shaped element(PA2) along an essentially horizontally oriented locus as output beam ofelectromagnetic radiation (LB′) which is undeviated and undisplaced fromthe essentially horizontally oriented locus of said input beam ofessentially horizontally oriented electromagnetic radiation (LB).

This is the case even when said retarder system (7) is caused to rotate.The result of said described retarder system (7) application being thatretardation is entered between orthogonal components of said inputelectromagnetic beam of radiation (LB).

FIG. 3 n 1 shows that the sixth additional present invention retardersystem (8) comprises first (BK1) and second (BK2) Berek-type retarderswhich each have an optical axes essentially perpendicular to a surfacethereof. As shown by FIG. 3 n 2, each of said first (BK1) and second(BK2) Berek-type retarders can have fast axis which are oriented otherthan parallel to one another, but for the presently described retardersystem it is assumed that the fast axes are aligned, (ie. an angle PHI(φ) of zero (0.0) degrees exists between fast axes of the two Berek-type(BK1) and (BK2) plates in FIG. 3 n 1. Said first and second Berek-typeretarders each present with first and second essentially parallel sides.Said first (BK1) and second (BK2) Berek-type retarders are oriented, asviewed in side elevation, with first (LS1) and second (RS1) sides of oneBerek-type retarder (BK1) being oriented other than parallel to first(LS2) and second (RS2) sides of the other Berek-type retarder (BK2). Inuse an incident beam of electromagnetic radiation (LB) is caused toimpinge upon one of said first (BK1) Berek-type retarder on one side(LS1) thereof, partially transmit therethrough then impinge upon thesecond Berek-type retarder (BK2), on one side thereof (LS2), andpartially transmit therethrough such that a polarized beam ofelectromagnetic radiation (LB′) passing through both of said first (BK1)and second (BK2) Berek-type retarders emerges from the second thereof ina polarized state with a phase angle between orthogonal componentstherein which is different than that in the incident beam ofelectromagnetic radiation (LB), and in a direction which is anessentially undeviated and undisplaced from the incident beam ofelectromagnetic radiation. This is the case even when said retardersystem (8) is caused to rotate. The result of said described retardersystem (8) application being that retardation is entered betweenorthogonal components of said input electromagnetic beam of radiation.For insight it is mentioned that, in general, a Berek-type retarder is auniaxial anisotropic plate with its optical axis essentiallyperpendicular to a surface thereof. The retardence introduced to anelectromagnetic beam caused to transmit therethrough is determined by atipping of said plate. The retardation system (8) having two suchBerek-type retarders present, is, it is noted, insensitive to smallangular deviations in an input electromagnetic beam as each platecontributes approximately hal of achieved retardence. This insensitivityresults because if the input electromagnetic beam is slightly changed,one of said plates will contribute slightly more (less), but the secondslightly less (more) retardence because of offsetting effective plate“tilts” with respect to electromagnetic beams input thereto. Also, saidretarder system (8) is very nearly ideal in that the PSI component ofthe retarder system (8) is very near a constant forty-five (45) degrees.One problem however, is that Berek-type retarder plates exhibit a(1/wavelength) retardence characteristic which, without more, makes useover a wide spectral range difficult.

A variation of the just described retarder system (8) applies to theseventh additional present invention retarder system (9) as well, withthe difference being that a FIG. 3 n 2 offset angle PHI (φ) other thanzero (0.0) is present between fast axes of the two Berek-type plates.The description of the system remains otherwise unchanged. The benefitderived, however, is that a flatter than (1/wavelength) retardationcharacteristic can be achieved thereby.

FIG. 3 o 1 serves as the pictorial reference for the eighth additionalpresent invention retarder system (10) which comprises first (BK1),second (BK2), third (BK3) and forth (BK4) Berek-type retarders whicheach have an optical axes essentially perpendicular to a surfacethereof, each of which first (BK1) and second (BK2) Berek-type retardershas a fast axis, said fast axes in said first (BK1) and second (BK2)Berek-type retarders being oriented essentially parallel to one another.This is exemplified by FIG. 3 o 2. Said first (BK1) Berek-type retarderpresents with first (LS1) and second (RS1) essentially parallel sidesand said second (BK2) Berek-type retarders each present with first (LS2)and second (RS2) essentially parallel sides, and said first (BK1) andsecond (BK2) Berek-type retarders are oriented, as viewed in sideelevation, with first (LS1) and second (RS1) sides of said firstBerek-type retarder being oriented other than parallel to first (LS2)and second (RS2) sides of said second (BK2) Berek-type retarder. In usean incident beam of electromagnetic radiation (LB) is caused to impingeupon said first (BK1) Berek-type retarder on said first side (LS1)thereof, partially transmit therethrough then impinge upon the second(BK2) Berek-type retarder, on said first (LS2) side thereof, andpartially transmit therethrough such that a polarized beam ofelectromagnetic radiation (LB′) passing through both of said first (BK1)and second (BK2) Berek-type retarders emerges from the second thereof ina polarized state with a phase angle between orthogonal componentstherein which is different than that in the incident beam ofelectromagnetic radiation (LB), and in a direction which is anessentially undeviated and undisplaced from the incident beam ofelectromagnetic radiation (LB). Each of which third (BK3) and forth(BK4) Berek-type retarders also has a fast axis, and said fast axes insaid third (BK3) and forth (BK4) Berek-type retarders are orientedessentially parallel to one another but other than parallel to theparallel fast axes of said first (BK1) and second (BK2) Berek-typeretarders. Said third (BK3) Berek-type retarder presents with first(LS3) and second (RS3) essentially parallel sides, and said forth (BK4)Berek-type presents with first (LS4) and second (RS4) essentiallyparallel sides, and said first third (BK3) and forth (BK4) Berek-typeretarders are oriented, as viewed in side elevation, with first (LS3)and second (RS3) sides of one of said third (BK3) Berek-type retarderbeing oriented other than parallel to first (LS4) and second (RS4) sidesof said forth (BK4) Berek-type retarder; such that in use an incidentbeam of electromagnetic radiation (LB′) exiting said second (BK2)Berek-type retarder is caused to impinge upon said third (BK3)Berek-type retarder on said first (LS3) side thereof, partially transmittherethrough then impinge upon said forth (BK4) Berek-type retarder onsaid first (LS4) side thereof, and partially transmit therethrough suchthat a polarized beam of electromagnetic radiation (LB″) passing throughsaid first (BK1), second (BK2), third (BK3) and forth (BK4) Berek-typeretarders emerges from the forth (BK4) thereof in a polarized state witha phase angle between orthogonal components therein which is differentthan that in the incident beam of electromagnetic radiation (LB) causedto impinge upon the first (LS1) side of said first (BK1) Berek-typeretarder, in a direction which is an essentially undeviated andundisplaced from said incident beam of electromagnetic radiation (LB).This is the case even when said retarder system (8) is caused to rotate.The result of said described retarder system (8) application being thatretardation is entered between orthogonal components of said inputelectromagnetic beam of radiation.

A ninth additional present invention retarder system (11) is alsopictorially represented by FIG. 3 o 1 and is similar to that justdescribed excepting that the Berek-type retarder plates (BK1) and (BK2)fast axes need not be parallel to one another and the Berek-typeretarder plates (BK3) and (BK4) need not be parallel to one another.However, if as a group Berek-type retarder plates ((BK1) and(BK2))/((BK3) and (BK4)) are parallel, they can be, but need not beparallel the fast axes of Berek-type retarder plates ((BK3) and(BK4))/((BK1) and (BK2)). This embodiment includes the case where allthe fast axes of all Berek-type retarders (BK1), (BK2), (BK3) and (BK4)are all different.

Turning now to FIG. 3 d, it is shown that the present invention systemsource of polychromatic radiation (QTH) as in FIG. 1, can, but notnecessarily, be a system for providing an output beam (OB) ofpolychromatic electromagnetic radiation which has a relatively broad andflattened intensity vs. wavelength characteristic over a wavelengthspectrum (generally identified as (LS)), said output beam (OB) ofpolychromatic electromagnetic radiation substantially being a comingledcomposite of a plurality of input beams, ((IB1) and (IB2)), ofpolychromatic electromagnetic radiation which individually do notprovide as relatively broad and flattened a intensity vs. wavelengthcharacteristic over said wavelength spectrum, as does said outputcomingled composite beam of polychromatic electromagnetic radiation,said system for providing an output beam of polychromaticelectromagnetic radiation which has a relatively broad and flattenedintensity vs. wavelength characteristic over a wavelength spectrumcomprising:

-   -   a. at least a first (S1) and a second (S2) source of        polychromatic electromagnetic radiation, ((IB1) and (IB2)        respectively); and    -   b. at least one electromagnetic beam combining (BCM) means        comprising an uncoated plate, (eg. uncoated fused silica or        glass etc. such that transmission characteristics thereof are        determined by angle-of-incidence and polarization state of a        beam of electromagnetic radiation).        The at least one electromagnetic beam combining means (BCM) is        positioned with respect to said first (S1) and second (S2)        sources of polychromatic electromagnetic radiation, ((IB1) and        (IB2) respectively), such that a beam of polychromatic        electromagnetic radiation (IB1) from said first (S1) source of        polychromatic electromagnetic radiation passes through said at        least one electromagnetic beam combining means (BCM), and such        that a beam of polychromatic electromagnetic radiation (IB2)        from said second (S2) source of polychromatic electromagnetic        radiation reflects from said at least one electromagnetic beam        combining means (BCM) and is comingled with said beam of        polychromatic electromagnetic radiation (IB1) from said first        source (S1) of polychromatic electromagnetic radiation which        passes through said at least one electromagnetic beam combining        means (BCM). The resultant beam of polychromatic electromagnetic        radiation (OB) is substantially an output beam of polychromatic        electromagnetic radiation which has a relatively broad and        flattened intensity vs. wavelength over a wavelength spectrum,        comprising said comingled composite of a plurality of input        beams of polychromatic electromagnetic radiation which        individually do not provide such a relatively broad and        flattened intensity vs. wavelength over a wavelength spectrum        characteristic. Also shown in FIG. 3 d are collimating lenses        (L1) and (L2) to provide collimated electromagnetic radiation to        the electromagnetic beam combining means (BCM), from first (S1)        and a second (S2) source of polychromatic electromagnetic        radiation, ((IB1) and (IB2) respectively).

FIG. 3 d further demonstrates an optional third source of polychromaticelectromagnetic radiation (S3) and a second electromagnetic beamcombining means (BCM′). The second electromagnetic beam combining means(BCM′) is positioned with respect to said comingled beam ofpolychromatic electromagnetic radiation (OB), (which has a relativelybroad and flattened intensity vs. wavelength over a wavelength spectrum,comprising wavelengths from sources (S1) and (S2), which exits said atleast a first electromagnetic beam combining means (BCM)), such thatsaid comingled beam of polychromatic electromagnetic radiation (OB)which has a relatively broad and flattened intensity vs. wavelength overa wavelength spectrum, passes through said second electromagnetic beamcombining means (BCM). The second electromagnetic beam combining means(BCM) is positioned with respect to said third source of polychromaticelectromagnetic radiation (S3) such that a beam of electromagneticradiation from said third source of polychromatic electromagneticradiation (S3) reflects from said second electromagnetic beam combiningmeans (BCM) to form a second resultant beam of polychromaticelectromagnetic radiation (OB′) which is substantially an output beam ofpolychromatic electromagnetic radiation which has an even morerelatively broadened and flattened intensity vs. wavelength over awavelength spectrum comprising said comingled composite of a pluralityof input beams of polychromatic electromagnetic radiation, (from sources(S1), (S2) and (S3)), which sources (S1), (S2) and (S3) individually donot provide such an even more relatively broadened and flattenedintensity vs. wavelength over a wavelength spectrum characteristic. Notethat first or second resultant beam of polychromatic electromagneticradiation (OB) (OB′) in FIG. 3 d can be comprise the source (QTH) inFIG. 1.

A system as shown in FIG. 3 d can also include a pivot(s) (PV) (PV′) toallow the beam combining means (BCM) and/or (BCM′), respectively, to berotated. This can be beneficially applied to allow selection of anoptimum angle at which a beam of electromagnetic radiation is caused toreflect therefrom in use. It is noted that the angle at which a beam ofelectromagnetic radiation approaches a beam combining means affects thepercent of an impinging beam which actually reflects therefrom andbecomes part of the output beam (OB), and where a beam sourcepositioning can be changed along with pivoting of a beam combiningmeans, this allows optimum combining of transmitted and reflected beams.Also, pivot with two degrees of rotational freedom can be applied tosimply effect coincidence of transmitted and reflected beams ofelectromagnetic radiation which originate from sources which are fixedin location.

Further, as described in the Disclosure of the invention Section of thisSpecification, as the polarizer in the present invention spectroscopicellipsometer system remains fixed in position during data acquisition,it is preferable that a source of electromagnetic radiation, and/or apresent Polarizer or Polarization State Generator be positioned orconfigured so as to pass predominately “S” Polarized electromagneticradiation, as referenced to said beam combining system. The reason forthis is that the split between transmission and reflection “S”polarization components is less, as a function of wavelength andelectromagnetic beam angle-of-incidence to said beam combining means,compared to that between the “P” components.

It is noted that any of said sources (S1) (S2) and (S3) of polychromaticelectromagnetic radiation can be Xenon or Duterium, and Quartz-Halogenlamps, or other suitable source.

It is also noted that a suitable electromagnetic beam combining (BCM)means can be made of glass or a fused silica plate, (preferablyuncoated), and can also be “Hot Mirrors” which reflect IR and transmitvisual wavelengths, or “Cold Mirrors” which reflect visible and transmitIR; mirror-type Beamsplitters or Pellicle Beamsplitters, such asdescribed in Edmund Industrial Optics Catalog Number N997A.

It is also generally noted that the present invention spectroscopicellipsometer system can, but not necessarily, utilize Zeiss Diode ArraySpectrometer Systems identified by manufacturer numbers in the group:(MMS1 (300–1150 nm); UV/VIS MMS (190–730 nm); UV MMS (190–400 nm); andIR MMS (900–2400 nm)) as Detector System (DET). Said identified Zeisssystems provide a very compact system comprising a multiplicity ofDetector Elements and provide focusing via a Focusing Element, Slit, andsingle concave holographic grating dispersive optics. However, anyfunctional multi-element spectroscopic Detector arrangement is withinthe scope of the present invention.

Contuinuing, FIG. 4 demonstrates the flow of a present invention methodof calibration of the spectroscopic ellipsometer portion of the presentinvention.

FIGS. 5–11 show Intensity vs. Wavelength for the seven (7)ellipsometrically different samples at each of five (5) imposedpolarization states. Results shown in FIGS. 5–7 respectively, are forSamples identified as 1, 2, 3, 4, 5, 6, and 7, which respectively haveOxide depths atop thereof of, (in Angstroms), 17.50; 103.0; 193.0;508.0; 1318.0; 4817.0 and 9961.0.

FIGS. 12 & 13 show PSI and DELTA values obtained for samples with thin(native), and thick, (9961 Angstrom), layers of Oxide thereupon. Allresults were obtained by fitting a mathematical model of the samplesystem and the spectroscopic ellipsometer system by regression ontoexperimental data.

FIGS. 14–16 are also included herein to provide insight to thePsuedo-Achromatic characteristics achieved by the FIG. 3 f Compensatordesign. FIG. 14 shows a plot of such a compensator retardationcharacteristic which depends as (1/wavelength), (dashed line), as wellas a present invention compensator charactristic, (solid line). Theimportant thing to note is that a selected range of wavelengths overwhich a retardation of between seventy-five (75) and one-hundred-thirty(130) degrees is developed, is much greater for the present inventioncompensator. A present invention spectroscopic rotatable compensatorellipsometer system can comprise at least one compensator(s) whichproduces a retardance of, preferably, between seventy-five (75) andone-hundred-thirty (130) degrees over a range of wavelengths defined bya selection from the group consisting of:

-   -   a. between one-hundred-ninety (190) and        seven-hundred-fifty (750) nanometers;    -   b. between two-hundred-forty-five (245) and nine-hundred (900)        nanometers;    -   c. between three-hundred-eighty (380) and        seventeen-hundred (1700) nanometers;    -   d. within a range of wavelengths defined by a maximum wavelength        (MAXW) and a minimum wavelength (MINW) wherein the ratio of        (MAXW)/(MINW) is at least one-and-eight-tenths (1.8). Acceptable        practice however, provides for the case wherein at least one of        said at least one compensator(s) provides a retardation vs.        wavelength characteristic retardation between thirty (30.0) and        less than one-hundred-thirty-five (135) degrees over a range of        wavelengths specified from MINW to MAXW by a selection from the        group consisting of:    -   a. MINW less than/equal to one-hundred-ninety (190) and MAXW        greater than/equal to seventeen-hundred (1700);    -   b. MINW less than/equal to two-hundred-twenty (220) and MAXW        greater than/equal to one-thousand (1000) nanometers;    -   c. within a range of wavelengths defined by a maximum wavelength        (MAXW) and a minimum wavelength (MINW) range where (MAXW)/(MINW)        is at least four-and one-half (4.5).        (NOTE, the specified vales and ranges can not be achieved by        single plates with (1/wavelength) retardation characteristics).

More specifically, FIG. 15 shows calculated retardation vs. wavelengthcurves for two compensators which demonstrate (1/wavelength) retardationcharacterics, (long and short dashed lines), and the retardation curve,(solid line), of a present invention assembly configuration asdemonstrated in FIG. 3 f which is arrived at by combining said tworetarders with a 45 degree angle between the fast axes thereof. FIG. 16shows a re-scaled plot of the solid line curve shown in FIG. 15.

Again, it is emphasised that the present Application does not applyCompensators in a system which causes continuous rotation thereof duringdata acquisition, but can benefit from a Compensator designed to provideessentially constant Polarization State Modification effects over aSpectroscopic range of wavelengths.

Having hereby disclosed the subject matter of the present invention, itshould be obvious that many modifications, substitutions, and variationsof the present invention are possible in view of the teachings. It istherefore to be understood that the invention may be practiced otherthan as specifically described, and should be limited in its breadth andscope only by the Claims.

1. A spectroscopic ellipsometer system comprising: a source ofpolychromatic electromagnetic radiation; a polarizer which is fixed inposition during data acquisition; a stage for supporting a samplesystem; an analyzer which is fixed in position during data acquisition;and a multi-element spectroscopic detector system; said spectroscopicellipsometer system further comprising at least one means fordiscretely, sequentially, modifying a Polarization state of a beam ofelectromagnetic radiation Provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization states,said means for discretely, sequentially, modifying a polarization stateof a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization state being present at at least one location selected fromthe group consisting of: between said polarizer and said stage forsupporting a sample system; and between said stage for supporting asample system and said analyzer; and positioned so that said beam ofelectromagnetic radiation transmits therethrough in use; in which saidat least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, involves at least one rotatablecompensator that changes the phase angle between orthogonal componentsof said electromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said at least onerotatable compensator comprises at least two per se. zero-orderwaveplates (MOA) and (MOB), said per se. zero-order waveplates (MOA) and(MOB) having their respective fast axes rotated to a position offsetfrom zero or ninety degrees with respect to one another, with a nominalvalue being forty-five degrees.
 2. A spectroscopic ellipsometer systemcomprising: a source of polychromatic electromagnetic radiation; apolarizer which is fixed in position during data acquisition; a stagefor supporting a sample system; an analyzer which is fixed in positionduring data acquisition; and a multi-element spectroscopic detectorsystem; said spectroscopic ellipsometer system further comprising atleast one means for discretely, sequentially, modifying a polarizationstate of a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization states, said means for discretely, sequentially, modifyinga polarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization state being present at at least one locationselected from the group consisting of: between said polarizer and saidstage for supporting a sample system; and between said stage forsupporting a sample system and said analyzer; and positioned so thatsaid beam of electromagnetic radiation transmits therethrough in use; inwhich said at least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, involves at least one rotatablecompensator that changes the phase angle between orthogonal componentsof said electromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said at least onerotatable compensator comprises a combination of at least a first (ZO1)and a second (ZO2) effective zero-order wave plate, said first (ZO1)effective zero-order wave plate being comprised of two multiple orderwaveplates (MOA1) and (MOB1) which are combined with the fast axesthereof oriented at a nominal ninety degrees to one another, and saidsecond (ZO2) effective zero-order wave plate being comprised of twomultiple order waveplates (MOA2) and (MOB2) which are combined with thefast axes thereof oriented at a nominal ninety degrees to one another;the fast axes (FAA2) and (FAB2) of the multiple order waveplates (MOA2)and (MOB2) in said second effective zero-order wave plate (ZO2) beingrotated to a position at a nominal forty-five degrees to the fast axes(FAA1) and (FAB1), respectively, of the multiple order waveplates (MOA1)and (MOB1) in said first effective zero-order waveplate (ZO1).
 3. Aspectroscopic ellipsometer system comprising: a source of polychromaticelectromagnetic radiation; a polarizer which is fixed in position duringdata acquisition; a stage for supporting a sample system; an analyzerwhich is fixed in position during data acquisition; and a multi-elementspectroscopic detector system; said spectroscopic ellipsometer systemfurther comprising at least one means for discretely, sequentially,modifying a polarization state of a beam of electromagnetic radiationprovided by said source of polychromatic electromagnetic radiationthrough a plurality of polarization states, said means for discretely,sequentially, modifying a polarization state of a beam ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization statebeing present at at least one location selected from the groupconsisting of: between said polarizer and said stage for supporting asample system; and between said stage for supporting a sample system andsaid analyzer; and positioned so that said beam of electromagneticradiation transmits therethrough in use; in which said at least onemeans for discretely, sequentially, modifying a polarization state of abeam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization states, involves at least one rotatable compensator thatchanges the phase angle between orthogonal components of saidelectromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said at least onerotatable compensator comprises at least a first (ZO1) and a second(ZO2) effective zero-order wave plate, said first (ZO1) effectivezero-order wave plate being comprised of two multiple order waveplates(MOA1) and (MOB1) which are combined with the fast axes thereof orientedat a nominal ninety degrees to one another, and said second (ZO2)effective zero-order wave plate being comprised of two multiple orderwaveplates (MOA2) and (MOB2) which are combined with the fast axesthereof oriented at a nominal ninety degrees to one another; the fastaxes (FAA2) and (FAB2) of the multiple order waveplates (MOA2) and(MOB2) in said second effective zero-order wave plate (ZO2) beingrotated to a position away from zero or ninety degrees with respect tothe fast axes (FAA1) and (FAB1), respectively, of the multiple orderwaveplates (MOA1) and (MOB1) in said first effective zero-orderwaveplate (ZO1).
 4. A spectroscopic ellipsometer system comprising: asource of polychromatic electromagnetic radiation; a polarizer which isfixed in position during data acquisition; a stage for supporting asample system; an analyzer which is fixed in position during dataacquisition; and a multi-element spectroscopic detector system; saidspectroscopic ellipsometer system further comprising at least one meansfor discretely, sequentially, modifying a polarization state of a beamof electromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization states,said means for discretely, sequentially, modifying a polarization stateof a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization state being present at at least one location selected fromthe group consisting of: between said polarizer and said stage forsupporting a sample system; and between said stage for supporting asample system and said analyzer; and positioned so that said beam ofelectromagnetic radiation transmits therethrough in use; in which saidat least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, involves at least one rotatablecompensator that changes the phase angle between orthogonal componentsof said electromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said at least onerotatable compensator comprises at least one zero-order waveplate,((MOA) or (MOB)), and at least one effective zero-order waveplate,((ZO2) or (ZO1) respectively), said effective zero-order wave plate,((ZO2) or (ZO1)), being comprised of two multiple order waveplates whichare combined with the fast axes thereof oriented at a nominal ninetydegrees to one another, the fast axes of the multiple order waveplatesin said effective zero-order wave plate, ((ZO2) or (ZO1)), being rotatedto a position away from zero or ninety degrees with respect to the fastaxis of the zero-order waveplate, ((MOA) or (MOB)).
 5. A spectroscopicellipsometer system comprising: a source of polychromaticelectromagnetic radiation; a polarizer which is fixed in position duringdata acquisition; a stage for supporting a sample system; an analyzerwhich is fixed in position during data acquisition; and a multi-elementspectroscopic detector system; said spectroscopic ellipsometer systemfurther comprising at least one means for discretely, sequentially,modifying a polarization state of a beam of electromagnetic radiationprovided by said source of polychromatic electromagnetic radiationthrough a plurality of polarization states, said means for discretely,sequentially, modifying a polarization state of a beam ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization statebeing present at at least one location selected from the groupconsisting of; between said polarizer and said stage for supporting asample system; and between said stage for supporting a sample system andsaid analyzer; and positioned so that said beam of electromagneticradiation transmits therethrough in use; in which said at least onemeans for discretely, sequentially, modifying a polarization state of abeam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization states, involves at least one rotatable compensator thatchanges the phase angle between orthogonal components of saidelectromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said at least onerotatable compensator comprises a first triangular shaped element, whichas viewed in side elevation presents with first and second sides whichproject to the left and right and downward from an upper point, whichfirst triangular shaped element first and second sides have reflectiveouter surfaces; said retarder system further comprising a secondtriangular shaped element which as viewed in side elevation presentswith first and second sides which project to the left and right anddownward from an upper point, said second triangular shaped elementbeing made of material which provides reflective interfaces on first andsecond sides inside thereof; said second triangular shaped element beingoriented with respect to the first triangular shaped element such thatthe upper point of said second triangular shaped element is orientedessentially vertically directly above the upper point of said firsttriangular shaped element; such that in use an input electromagneticbeam of radiation caused to approach one of said first and second sidesof said first triangular shaped element along an essentiallyhorizontally oriented locus, is caused to externally reflect from anouter surface thereof and travel along a locus which is essentiallyupwardly vertically oriented, then enter said second triangular shapedelement and essentially totally internally reflect from one of saidfirst and second sides thereof, then proceed along an essentiallyhorizontal locus and essentially totally internally reflect from theother of said first and second sides and proceed along an essentiallydownward vertically oriented locus, then externally reflect from theother of said first and second sides of said first triangular shapedelements and proceed along an essentially horizontally oriented locuswhich is undeviated and undisplaced from the essentially horizontallyoriented locus of said input beam of essentially horizontally orientedelectromagnetic radiation; with a result being that retardation isentered between orthogonal components of said input electromagnetic beamof radiation.
 6. A spectroscopic ellipsometer system comprising: asource of polychromatic electromagnetic radiation; a polarizer which isfixed in position during data acquisition; a stage for supporting asample system; an analyzer which is fixed in position during dataacquisition; and a multi-element spectroscopic detector system; saidspectroscopic ellipsometer system further comprising at least one meansfor discretely, sequentially, modifying a polarization state of a beamof electromagnetic radiation Provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization states,said means for discretely, sequentially, modifying a polarization stateof a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization state being present at at least one location selected fromthe group consisting of: between said polarizer and said stage forsupporting a sample system; and between said stage for supporting asample system and said analyzer; and positioned so that said beam ofelectromagnetic radiation transmits therethrough in use; in which saidat least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, involves at least one rotatablecompensator that changes the phase angle between orthogonal componentsof said electromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said at least onerotatable compensator comprises, as viewed in upright side elevation,first and second orientation adjustable mirrored elements which eachhave reflective surfaces; said compensator system further comprising athird element which, as viewed in upright side elevation, presents withfirst and second sides which project to the left and right and downwardfrom an upper point, said third element being made of material whichprovides reflective interfaces on first and second sides inside thereof;said third element being oriented with respect to said first and secondorientation adjustable mirrored elements such that in use an inputelectromagnetic beam of radiation caused to approach one of said firstand second orientation adjustable mirrored elements along an essentiallyhorizontally oriented locus, is caused to externally reflect therefromand travel along a locus which is essentially upwardly verticallyoriented, then enter said third element and essentially totallyinternally reflect from one of said first and second sides thereof, thenproceed along an essentially horizontal locus and essentially totallyinternally reflect from the other of said first and second sides andproceed along an essentially downward vertically oriented locus, thenreflect from the other of said first and second orientation adjustablemirrored elements and proceed along an essentially horizontally orientedpropagation direction locus which is essentially undeviated andundisplaced from the essentially horizontally oriented propagationdirection locus of said input beam of essentially horizontally orientedelectromagnetic radiation; with a result being that retardation isentered between orthogonal components of said input electromagnetic beamof radiation.
 7. A spectroscopic ellipsometer system comprising: asource of polychromatic electromagnetic radiation; a polarizer which isfixed in position during data acquisition; a stage for supporting asample system; an analyzer which is fixed in position during dataacquisition; and a multi-element spectroscopic detector system; saidspectroscopic ellipsometer system further comprising at least one meansfor discretely, sequentially, modifying a polarization state of a beamof electromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization states,said means for discretely, sequentially, modifying a polarization stateof a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization state being present at at least one location selected fromthe group consisting of: between said polarizer and said stage forsupporting a sample system; and between said stage for supporting asample system and said analyzer; and positioned so that said beam ofelectromagnetic radiation transmits therethrough in use; in which saidat least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, involves at least one rotatablecompensator that changes the phase angle between orthogonal componentsof said electromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said at least onerotatable compensator comprises a parallelogram shaped element which, asviewed in side elevation, has top and bottom sides parallel to oneanother, both said top and bottom sides being oriented essentiallyhorizontally, said retarder system also having right and left sidesparallel to one another, both said right and left sides being orientedat an angle to horizontal, said retarder being made of a material withan index of refraction greater than that of a surrounding ambient; suchthat in use an input beam of electromagnetic radiation caused to enter aside of said retarder selected from the group consisting of: right andleft; along an essentially horizontally oriented locus, is caused todiffracted inside said retarder system and follow a locus which causesit to essentially totally internally reflect from internal interfaces ofboth said top and bottom sides, and emerge from said retarder systemfrom a side selected from the group consisting of left and rightrespectively; along an essentially horizontally oriented locus which isundeviated and undisplaced from the essentially horizontally orientedlocus of said input beam of essentially horizontally orientedelectromagnetic radiation; with a result being that retardation isentered between orthogonal components of said input electromagnetic beamof radiation.
 8. A spectroscopic ellipsometer system comprising: asource of polychromatic electromagnetic radiation; a polarizer which isfixed in position during data acquisition; a stage for supporting asample system; an analyzer which is fixed in position during dataacquisition; and a multi-element spectroscopic detector system; saidspectroscopic ellipsometer system further comprising at least one meansfor discretely, sequentially, modifying a polarization state of a beamof electromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization states,said means for discretely, sequentially, modifying a polarization stateof a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization state being present at at least one location selected fromthe group consisting of: between said polarizer and said stage forsupporting a sample system; and between said stage for supporting asample system and said analyzer; and positioned so that said beam ofelectromagnetic radiation transmits therethrough in use; in which saidat least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, involves at least one rotatablecompensator that changes the phase angle between orthogonal componentsof said electromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said at least onerotatable compensator comprises first and second triangular shapedelements, said first triangular shaped element, as viewed in sideelevation, presenting with first and second sides which project to theleft and right and downward from an upper point, said first triangularshaped element further comprising a third side which is orientedessentially horizontally and which is continuous with, and present belowsaid first and second sides; and said second triangular shaped element,as viewed in side elevation, presenting with first and second sideswhich project to the left and right and upward from an upper point, saidsecond triangular shaped element further comprising a third side whichis oriented essentially horizontally and which is continuous with, andpresent above said first and second sides; said first and secondtriangular shaped elements being positioned so that a rightmost side ofone of said first and second triangular shaped elements is in contactwith a leftmost side of the other of said first and second triangularshaped elements over at least a portion of the lengths thereof; saidfirst and second triangular shaped elements each being made of materialwith an index of refraction greater than that of a surrounding ambient;such that in use an input beam of electromagnetic radiation caused toenter a side of a triangular shaped element selected from the groupconsisting of: first and second; not in contact with said othertriangular shape element, is caused to diffracted inside said retarderand follow a locus which causes it to essentially totally internallyreflect from internal interfaces of said third sides of each of saidfirst and second triangular shaped elements, and emerge from a side ofsaid triangular shaped element selected from the group consisting of:second and first; not in contact with said other triangular shapeelement, along an essentially horizontally oriented locus which isundeviated and undisplaced from the essentially horizontally orientedlocus of said input beam of essentially horizontally orientedelectromagnetic radiation; with a result being that retardation isentered between orthogonal components of said input electromagnetic beamof radiation.
 9. A spectroscopic ellipsometer system comprising: asource of polychromatic electromagnetic radiation; a polarizer which isfixed in position during data acquisition; a stage for supporting asample system; an analyzer which is fixed in position during dataacquisition; and a multi-element spectroscopic detector system; saidspectroscopic ellipsometer system further comprising at least one meansfor discretely, sequentially, modifying a polarization state of a beamof electromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization states,said means for discretely, sequentially, modifying a polarization stateof a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization state being present at at least one location selected fromthe group consisting of: between said polarizer and said stage forsupporting a sample system; and between said stage for supporting asample system and said analyzer; and positioned so that said beam ofelectromagnetic radiation transmits therethrough in use; in which saidat least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, involves at least one rotatablecompensator that changes the phase angle between orthogonal componentsof said electromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said at least onerotatable compensator comprises a triangular shaped element, which asviewed in side elevation presents with first and second sides whichproject to the left and right and downward from an upper point, saidretarder system further comprising a third side which is orientedessentially horizontally and which is continuous with, and present belowsaid first and second sides; said retarder system being made of amaterial with an index of refraction greater than that of a surroundingambient; such that in use a an input beam of electromagnetic radiationcaused to enter a side of said retarder system selected from the groupconsisting of: first and second; along an essentially horizontallyoriented locus, is caused to diffracted inside said retarder system andfollow a locus which causes it to essentially totally internally reflectfrom internal interface of said third sides, and emerge from saidretarder from a side selected from the group consisting of second andfirst respectively; along an essentially horizontally oriented locuswhich is undeviated and undisplaced from the essentially horizontallyoriented locus of said input beam of essentially horizontally orientedelectromagnetic radiation; with a result being that retardation isentered between orthogonal components of said input electromagnetic beamof radiation.
 10. A spectroscopic ellipsometer system comprising: asource of polychromatic electromagnetic radiation; a polarizer which isfixed in position during data acquisition; a stage for supporting asample system; an analyzer which is fixed in position during dataacquisition; and a multi-element spectroscopic detector system; saidspectroscopic ellipsometer system further comprising at least one meansfor discretely, sequentially, modifying a polarization state of a beamof electromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization states,said means for discretely, sequentially, modifying a polarization stateof a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization state being present at at least one location selected fromthe group consisting of: between said polarizer and said stage forsupporting a sample system; and between said stage for supporting asample system and said analyzer; and positioned so that said beam ofelectromagnetic radiation transmits therethrough in use; in which saidat least one means for discretely, sequentially modifying a polarizationstate of a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization states, involves at least one rotatable compensator thatchances the phase angle between orthogonal components of saidelectromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said at least onerotatable compensator comprises first and second Berek-type retarderswhich each have an optical axes essentially perpendicular to a surfacethereof, each of which first and second Berek-type retarders has a fastaxis, said fast axes in said first and second Berek-type retarders beingoriented in an orientation selected from the group consisting of:parallel to one another; and other than parallel to one another; saidfirst and second Berek-type retarders each presenting with first andsecond essentially parallel sides, and said first and second Berek-typeretarders being oriented, as viewed in side elevation, with first andsecond sides of one Berek-type retarder being oriented other thanparallel to first and second sides of the other Berek-type retarder;such that in use an incident beam of electromagnetic radiation is causedto impinge upon one of said first and second Berek-type retarders on oneside thereof, partially transmit therethrough then impinge upon thesecond Berek-type retarder, on one side thereof, and partially transmittherethrough such that a polarized beam of electromagnetic radiationpassing through both of said first and second Berek-type retardersemerges from the second thereof in a polarized state with a phase anglebetween orthogonal components therein which is different than that inthe incident beam of electromagnetic radiation, and in a propagationdirection which is essentially undeviated and undisplaced from theincident beam of electromagnetic radiation; with a result being thatretardation is entered between orthogonal components of said inputelectromagnetic beam of radiation.
 11. A spectroscopic ellipsometersystem comprising: a source of polychromatic electromagnetic radiation;a polarizer which is fixed in position during data acquisition; a stagefor supporting a sample system; an analyzer which is fixed in positionduring data acquisition; and a multi-element spectroscopic detectorsystem; said spectroscopic ellipsometer system further comprising atleast one means for discretely, sequentially, modifying a polarizationstate of a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization states, said means for discretely, sequentially, modifyinga polarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization state being present at at least one locationselected from the group consisting of: between said polarizer and saidstage for supporting a sample system; and between said stage forsupporting a sample system and said analyzer; and positioned so thatsaid beam of electromagnetic radiation transmits therethrough in use; inwhich said at least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, involves at least one rotatablecompensator that changes the phase angle between orthogonal componentsof said electromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said at least onerotatable compensator comprises first and second Berek-type retarderswhich each have an optical axes essentially perpendicular to a surfacethereof, each of which first and second Berek-type retarders has a fastaxis, said fast axes in said first and second Berek-type retarders beingoriented other than parallel to one another; said first and secondBerek-type retarders each presenting with first and second essentiallyparallel sides, and said first and second Berek-type, retarders beingoriented, as viewed in side elevation, with first and second sides ofone Berek-type retarder being oriented other than parallel to first andsecond sides of the other Berek-type retarder; such that in use anincident beam of electromagnetic radiation is caused to impinge upon oneof said first and second Berek-type retarders on one side thereof,partially transmit therethrough then impinge upon the second Berek-typeretarder, on one side thereof, and partially transmit therethrough suchthat a polarized beam of electromagnetic radiation passing through bothof said first and second Berek-type retarders emerges from the secondthereof in a polarized state with a phase angle between orthogonalcomponents therein which is different than that in the incident beam ofelectromagnetic radiation, and in a propagation direction which isessentially undeviated and undisplaced from the incident beam ofelectromagnetic radiation, said compensator system further comprisingthird and forth Berek-type retarders which each have an optical axesessentially perpendicular to a surface thereof, each of which third andforth Berek-type retarders has a fast axis, said fast axes in said thirdand forth Berek-type retarders being oriented other than parallel to oneanother, said third and forth Berek-type retarders each presenting withfirst and second essentially parallel sides, and said third and forthBerek-type retarders being oriented, as viewed in side elevation, withfirst and second sides of one of said third and forth Berek-typeretarders being oriented other than parallel to first and second sidesof said forth Berek-type retarder; such that in use an incident beam ofelectromagnetic radiation exiting said second Berek-type retarder iscaused to impinge upon said third Berek-type retarder on one sidethereof, partially transmit therethrough then impinge upon said forthBerek-type retarder on one side thereof, and partially transmittherethrough such that a polarized beam of electromagnetic radiationpassing through said first, second, third and forth Berek-type retardersemerges from the forth thereof in a polarized state with a phase anglebetween orthogonal components therein which is different than that inthe incident beam of electromagnetic radiation caused to impinge uponthe first side of said first Berek-type retarder, and in a directionwhich is essentially undeviated and undisplaced from said incident beamof electromagnetic radiation; with a result being that retardation isentered between orthogonal components of said input electromagnetic beamof radiation.
 12. A spectroscopic ellipsometer system comprising: asource of polychromatic electromagnetic radiation: a polarizer which isfixed in position during data acquisition; a stage for supporting asample system; an analyzer which is fixed in position during dataacquisition; and a multi-element spectroscopic detector system; saidspectroscopic ellipsometer system further comprising at least one meansfor discretely, sequentially, modifying a polarization state of a beamof electromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization states,said means for discretely, sequentially, modifying a polarization stateof a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization state being present at at least one location selected fromthe group consisting of: between said polarizer and said stage forsupporting a sample system; and between said stage for supporting asample system and said analyzer; and positioned so that said beam ofelectromagnetic radiation transmits therethrough in use; in which saidat least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, involves at least one rotatablecompensator that changes the phase angle between orthogonal componentsof said electromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said at least onerotatable compensator comprises first, second, third and forthBerek-type retarders which each have an optical axes essentiallyperpendicular to a surface thereof, each of which first and secondBerek-type retarders has a fast axis, said fast axes in said first andsecond Berek-type retarders being oriented essentially parallel to oneanother; said first and second Berek-type retarders each presenting withfirst and second essentially parallel sides, and said first and secondBerek-type retarders being oriented, as viewed in side elevation, withfirst and second sides of one Berek-type retarder being oriented otherthan parallel to first and second sides of the other Berek-typeretarder; such that in use an incident beam of electromagnetic radiationis caused to impinge upon one of said first and second Berek-typeretarders on one side thereof, partially transmit therethrough thenimpinge upon the second Berek-type retarder, on one side thereof, andpartially transmit therethrough such that a polarized beam ofelectromagnetic radiation passing through both of said first and secondBerek-type retarders emerges from the second thereof in a polarizedstate with a phase angle between orthogonal components therein which isdifferent than that in the incident beam of electromagnetic radiation,and in a propagation direction which is essentially undeviated andundisplaced from the incident beam of electromagnetic radiation; each ofwhich third and forth Berek-type retarders has a fast axis, said fastaxes in said third and forth Berek-type retarders being orientedessentially parallel to one another but other than parallel to the fastaxes of said first and second Berek-type retarders, said third and forthBerek-type retarders each presenting with first and second essentiallyparallel sides, and said third and forth Berek-type retarders beingoriented, as viewed in side elevation, with first and second sides ofone of said third and forth Berek-type retarders being oriented otherthan parallel to first and second sides of said forth Berek-typeretarder; such that in use an incident beam of electromagnetic radiationexiting said second Berek-type retarder is caused to impinge upon saidthird Berek-type retarder on one side thereof, partially transmittherethrough then impinge upon said forth Berek-type retarder on oneside thereof, and partially transmit therethrough such that a polarizedbeam of electromagnetic radiation passing through said first, second,third and forth Berek-type retarders emerges from the forth thereof in apolarized state with a phase angle between orthogonal components thereinwhich is different than that in the incident beam of electromagneticradiation caused to impinge upon the first side of said first Berek-typeretarder, and in a direction which is essentially undeviated andundisplaced from said incident beam of electromagnetic radiation; with aresult being that retardation is entered between orthogonal componentsof said input electromagnetic beam of radiation.
 13. A spectroscopicellipsometer system comprising: a source of polychromaticelectromagnetic radiation; a polarizer which is fixed in position duringdata acquisition; a stage for supporting a sample system; an analyzerwhich is fixed in position during data acquisition; and a multi-elementspectroscopic detector system; said spectroscopic ellipsometer systemfurther comprising at least one means for discretely, sequentially,modifying a polarization state of a beam of electromagnetic radiationprovided by said source of polychromatic electromagnetic radiationthrough a plurality of polarization states, said means for discretely,sequentially, modifying a polarization state of a beam ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization statebeing present at at least one location selected from the groupconsisting of: between said polarizer and said stage for supporting asample system; and between said stage for supporting a sample system andsaid analyzer; and positioned so that said beam of electromagneticradiation transmits therethrough in use; in which said at least onemeans for discretely, sequentially, modifying a polarization state of abeam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization states, involves at least one rotatable compensator thatchanges the phase angle between orthogonal components of saidelectromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which said source ofpolychromatic electromagnetic radiation comprises an output beam ofpolychromatic electromagnetic radiation which has a relatively broad andflattened intensity vs. wavelength characteristic over a wavelengthspectrum for use in said present invention systems, provides that saidoutput beam of polychromatic electromagnetic radiation substantially bea comingled composite of a plurality of input beams of polychromaticelectromagnetic radiation which individually do not provide asrelatively broad and flattened a intensity vs. wavelength characteristicover said wavelength spectrum, as does said output comingled compositebeam of polychromatic electromagnetic radiation, said system forproviding an output beam of polychromatic electromagnetic radiationwhich has a relatively broad and flattened intensity vs. wavelengthcharacteristic over a wavelength spectrum comprising: a. at least afirst and a second source of polychromatic electromagnetic radiation;and b. at least a first electromagnetic beam combining means; said atleast a first electromagnetic beam combining means being positioned withrespect to said first and second sources of polychromaticelectromagnetic radiation such that a beam of polychromaticelectromagnetic radiation from said first source of polychromaticelectromagnetic radiation passes through said at least a firstelectromagnetic beam combining means, and such that a beam ofpolychromatic electromagnetic radiation from said second source ofpolychromatic electromagnetic radiation reflects from said at least afirst electromagnetic beam combining means and is comingled with saidbeam of polychromatic electromagnetic radiation from said first sourceof polychromatic electromagnetic radiation which passes through said atleast a first electromagnetic beam combining means, said resultant beamof polychromatic electromagnetic radiation substantially being saidoutput beam of polychromatic electromagnetic radiation which has arelatively broad and flattened intensity vs. wavelength over awavelength spectrum, comprising said comingled composite of a pluralityof input beams of polychromatic electromagnetic radiation whichindividually do not provide such a relatively broad and flattenedintensity vs. wavelength over a wavelength spectrum characteristic. 14.A spectroscopic ellipsometer system comprising: a source ofpolychromatic electromagnetic radiation; a polarizer which is fixed inposition during data acquisition; a stage for supporting a samplesystem; an analyzer which is fixed in position during data acquisition;and a multi-element spectroscopic detector system; said spectroscopicellipsometer system further comprising at least one means fordiscretely, sequentially, modifying a polarization state of a beam ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization states,said means for discretely, sequentially, modifying a polarization stateof a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization state being present at at least one location selected fromthe group consisting of: between said polarizer and said stage forsupporting a sample system; and between said stage for supporting asample system and said analyzer; and positioned so that said beam ofelectromagnetic radiation transmits therethrough in use; in which saidat least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, involves at least one rotatablecompensator that changes the phase angle between orthogonal componentsof said electromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; in which at least one selectionis made from the group consisting of: at least one of said polarizer andanalyzer has its azimuthal angle set to a selection from the groupconsisting of: essentially plus forty-five (45) degrees; and essentiallyminus forty-five (45) degrees; and in which said polarizer is set so asto select an “S” polarized electromagnetic beam component referenced tothe source of said electromagnetic beam.
 15. A method of calibrating aspectroscopic ellipsometer system comprising the steps of: a. providinga spectroscopic ellipsometer system comprising: a source ofpolychromatic electromagnetic radiation; a polarizer which remains fixedin position during data acquisition; a stage for supporting a samplesystem; an analyzer which remains fixed in position during dataacquisition; and a multi-element spectroscopic detector system; saidspectroscopic ellipsometer system further comprising at least onerotatable compensator means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, said means for discretely,sequentially, modifying a polarization state of a beam ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization statesbeing present at at least one location selected from the groupconsisting of: between said polarizer and said stage for supporting asample system; and between said stage for supporting a sample system andsaid analyzer; and positioned so that said beam of electromagneticradiation transmits therethrough in use; said method further comprising,in any functional order, the steps of: b. for each of at least twoellipsometrically distinguished sample systems, obtaining at least onemulti-dimensional data set(s) comprising intensity as a function ofwavelength and a function of a plurality of discrete settings of said atleast one means for discretely, sequentially, modifying a polarizationstate of a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation; c. providing a mathematicalmodel of the ellipsometer system, including provision for accounting forthe settings of said at least one means for discretely, sequentially,modifying a polarization state of a beam of electromagnetic radiationprovided by said source of polychromatic electromagnetic radiationutilized in step b; and d. by simultaneous mathematical regression ontosaid data sets, evaluating parameters in said mathematical model,including polarization state changing aspects of each of said pluralityof discrete settings of said at least one means for discretely,sequentially, modifying a polarization state of a beam ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation; in which the step of providing a means fordiscretely, sequentially, modifying a polarization state of a beam ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization states,involves providing at least one compensator means that changes the phaseangle between orthogonal components of said electromagnetic beam ofradiation provided by said source of polychromatic electromagneticradiation; said at least one compensator means comprising at least onerotatable compensator selected from the group consisting of: a. aselection from the group consisting of: a single element compensator;and a multiple element compensator; b. a compensator comprised of atleast two per se. zero-order waveplates (MOA) and (MOB), said per se.zero-order waveplates (MOA) and (MOB) having their respective fast axesrotated to a position offset from zero or ninety degrees with respect toone another, with a nominal value being forty-five degrees; c. acompensator comprised of a combination of at least a first (ZO1) and asecond (ZO2) effective zero-order wave plate, said first (ZO1) effectivezero-order wave plate being comprised of two multiple order waveplates(MOA1) and (MOB1) which are combined with the fast axes thereof orientedat a nominal ninety degrees to one another, and said second (ZO2)effective zero-order wave plate being comprised of two multiple orderwaveplates (MOA2) and (MOB2) which are combined with the fast axesthereof oriented at a nominal ninety degrees to one another; the fastaxes (FAA2) and (FAB2) of the multiple order waveplates (MOA2) and(MOB2) in said second effective zero-order wave plate (ZO2) beingrotated to a position at a nominal forty-five degrees to the fast axes(FAA1) and (FAB1), respectively, of the multiple order waveplates (MOA1)and (MOB1) in said first effective zero-order waveplate (ZO1); d. acompensator comprised of a combination of at least a first (ZO1) and asecond (ZO2) effective zero-order wave plate, said first (ZO1) effectivezero-order wave plate being comprised of two multiple order waveplates(MOA1) and (MOB1) which are combined with the fast axes thereof orientedat a nominal ninety degrees to one another, and said second (ZO2)effective zero-order wave plate being comprised of two multiple orderwaveplates (MOA2) and (MOB2) which are combined with the fast axesthereof oriented at a nominal ninety degrees to one another; the fastaxes (FAA2) and (FAB2) of the multiple order waveplates (MOA2) and(MOB2) in said second effective zero-order wave plate (ZO2) beingrotated to a position away from zero or ninety degrees with respect tothe fast axes (FAA1) and (FAB1), respectively, of the multiple orderwaveplates (MOA1) and (MOB1) in said first effective zero-orderwaveplate (ZO1); e. a compensator comprised of at least one zero-orderwaveplate, ((MOA) or (MOB)), and at least one effective zero-orderwaveplate, ((ZO2) or (ZO1) respectively), said effective zero-order waveplate, ((ZO2) or (ZO1)), being comprised of two multiple orderwaveplates which are combined with the fast axes thereof oriented at anominal ninety degrees to one another, the fast axes of the multipleorder waveplates in said effective zero-order wave plate, ((ZO2) or(ZO1)), being rotated to a position away from zero or ninety degreeswith respect to the fast axis of the zero-order waveplate, ((MOA) or(MOB)); f. a compensator system comprised of a first triangular shapedelement, which as viewed in side elevation presents with first andsecond sides which project to the left and right and downward from anupper point, which first triangular shaped element first and secondsides have reflective outer surfaces; said retarder system furthercomprising a second triangular shaped element which as viewed in sideelevation presents with first and second sides which project to the leftand right and downward from an upper point, said second triangularshaped element being made of material which provides reflectiveinterfaces on first and second sides inside thereof; said secondtriangular shaped element being oriented with respect to the firsttriangular shaped element such that the upper point of said secondtriangular shaped element is oriented essentially vertically directlyabove the upper point of said first triangular shaped element; such thatin use an input electromagnetic beam of radiation caused to approach oneof said first and second sides of said first triangular shaped elementalong an essentially horizontally oriented locus, is caused toexternally reflect from an outer surface thereof and travel along alocus which is essentially upwardly vertically oriented, then enter saidsecond triangular shaped element and essentially totally internallyreflect from one of said first and second sides thereof, then proceedalong an essentially horizontal locus and essentially totally internallyreflect from the other of said first and second sides and proceed alongan essentially downward vertically oriented locus, then externallyreflect from the other of said first and second sides of said firsttriangular shaped elements and proceed along an essentially horizontallyoriented locus which is undeviated and undisplaced from the essentiallyhorizontally oriented locus of said input beam of essentiallyhorizontally oriented electromagnetic radiation; with a result beingthat retardation is entered between orthogonal components of said inputelectromagnetic beam of radiation; g. a compensator system comprised of,as viewed in upright side elevation, first and second orientationadjustable mirrored elements which each have reflective surfaces; saidcompensator system further comprising a third element which, as viewedin upright side elevation, presents with first and second sides whichproject to the left and right and downward from an upper point, saidthird element being made of material which provides reflectiveinterfaces on first and second sides inside thereof; said third elementbeing oriented with respect to said first and second orientationadjustable mirrored elements such that in use an input electromagneticbeam of radiation caused to approach one of said first and secondorientation adjustable mirrored elements along an essentiallyhorizontally oriented locus, is caused to externally reflect therefromand travel along a locus which is essentially upwardly verticallyoriented, then enter said third element and essentially totallyinternally reflect from one of said first and second sides thereof, thenproceed along an essentially horizontal locus and essentially totallyinternally reflect from the other of said first and second sides andproceed along an essentially downward vertically oriented locus, thenreflect from the other of said first and second orientation adjustablemirrored elements and proceed along an essentially horizontally orientedpropagation direction locus which is essentially undeviated andundisplaced from the essentially horizontally oriented propagationdirection locus of said input beam of essentially horizontally orientedelectromagnetic radiation; with a result being that retardation isentered between orthogonal components of said input electromagnetic beamof radiation; h. a compensator system comprised of a parallelogramshaped element which, as viewed in side elevation, has top and bottomsides parallel to one another, both said top and bottom sides beingoriented essentially horizontally, said retarder system also havingright and left sides parallel to one another, both said right and leftsides being oriented at an angle to horizontal, said retarder being madeof a material with an index of refraction greater than that of asurrounding ambient; such that in use an input beam of electromagneticradiation caused to enter a side of said retarder selected from thegroup consisting of: right and left; along an essentially horizontallyoriented locus, is caused to diffracted inside said retarder system andfollow a locus which causes it to essentially totally internally reflectfrom internal interfaces of both said top and bottom sides, and emergefrom said retarder system from a side selected from the group consistingof: left and right respectively; along an essentially horizontallyoriented locus which is undeviated and undisplaced from the essentiallyhorizontally oriented locus of said input beam of essentiallyhorizontally oriented electromagnetic radiation; with a result beingthat retardation is entered between orthogonal components of said inputelectromagnetic beam of radiation; i. a compensator system comprised offirst and second triangular shaped elements, said first triangularshaped element, as viewed in side elevation, presenting with first andsecond sides which project to the left and right and downward from anupper point, said first triangular shaped element further comprising athird side which is oriented essentially horizontally and which iscontinuous with, and present below said first and second sides; and saidsecond triangular shaped element, as viewed in side elevation,presenting with first and second sides which project to the left andright and upward from an upper point, said second triangular shapedelement further comprising a third side which is oriented essentiallyhorizontally and which is continuous with, and present above said firstand second sides; said first and second triangular shaped elements beingpositioned so that a rightmost side of one of said first and secondtriangular shaped elements is in contact with a leftmost side of theother of said first and second triangular shaped elements over at leasta portion of the lengths thereof; said first and second triangularshaped elements each being made of material with an index of refractiongreater than that of a surrounding ambient; such that in use an inputbeam of electromagnetic radiation caused to enter a side of a triangularshaped element selected from the group consisting of: first and second;not in contact with said other triangular shape element, is caused todiffracted inside said retarder and follow a locus which causes it toessentially totally internally reflect from internal interfaces of saidthird sides of each of said first and second triangular shaped elements,and emerge from a side of said triangular shaped element selected fromthe group consisting of: second and first; not in contact with saidother triangular shape element, along an essentially horizontallyoriented locus which is undeviated and undisplaced from the essentiallyhorizontally oriented locus of said input beam of essentiallyhorizontally oriented electromagnetic radiation; with a result beingthat retardation is entered between orthogonal components of said inputelectromagnetic beam of radiation; j. a compensator system comprised ofa triangular shaped element, which as viewed in side elevation presentswith first and second sides which project to the left and right anddownward from an upper point, said retarder system further comprising athird side which is oriented essentially horizontally and which iscontinuous with, and present below said first and second sides; saidretarder system being made of a material with an index of refractiongreater than that of a surrounding ambient; such that in use a an inputbeam of electromagnetic radiation caused to enter a side of saidretarder system selected from the group consisting of: first and second;along an essentially horizontally oriented locus, is caused todiffracted inside said retarder system and follow a locus which causesit to essentially totally internally reflect from internal interface ofsaid third sides, and emerge from said retarder from a side selectedfrom the group consisting of: second and first respectively; along anessentially horizontally oriented locus which is undeviated andundisplaced from the essentially horizontally oriented locus of saidinput beam of essentially horizontally oriented electromagneticradiation; with a result being that retardation is entered betweenorthogonal components of said input electromagnetic beam of radiation;k. a compensator system comprised of first and second Berek-typeretarders which each have an optical axes essentially perpendicular to asurface thereof, each of which first and second Berek-type retarders hasa fast axis, said fast axes in said first and second Berek-typeretarders being oriented in an orientation selected from the groupconsisting of: parallel to one another; and other than parallel to oneanother; said first and second Berek-type retarders each presenting withfirst and second essentially parallel sides, and said first and secondBerek-type retarders being oriented, as viewed in side elevation, withfirst and second sides of one Berek-type retarder being oriented otherthan parallel to first and second sides of the other Berek-typeretarder; such that in use an incident beam of electromagnetic radiationis caused to impinge upon one of said first and second Berek-typeretarders on one side thereof, partially transmit therethrough thenimpinge upon the second Berek-type retarder, on one side thereof, andpartially transmit therethrough such that a polarized beam ofelectromagnetic radiation passing through both of said first and secondBerek-type retarders emerges from the second thereof in a polarizedstate with a phase angle between orthogonal components therein which isdifferent than that in the incident beam of electromagnetic radiation,and in a propagation direction which is essentially undeviated andundisplaced from the incident beam of electromagnetic radiation; with aresult being that retardation is entered between orthogonal componentsof said input electromagnetic beam of radiation; l. a compensator systemcomprised of first and second Berek-type retarders which each have anoptical axes essentially perpendicular to a surface thereof, each ofwhich first and second Berek-type retarders has a fast axis, said fastaxes in said first and second Berek-type retarders being oriented otherthan parallel to one another; said first and second Berek-type retarderseach presenting with first and second essentially parallel sides, andsaid first and second Berek-type retarders being oriented, as viewed inside elevation, with first and second sides of one Berek-type retarderbeing oriented other than parallel to first and second sides of theother Berek-type retarder; such that in use an incident beam ofelectromagnetic radiation is caused to impinge upon one of said firstand second Berek-type retarders on one side thereof, partially transmittherethrough then impinge upon the second Berek-type retarder, on oneside thereof, and partially transmit therethrough such that a polarizedbeam of electromagnetic radiation passing through both of said first andsecond Berek-type retarders emerges from the second thereof in apolarized state with a phase angle between orthogonal components thereinwhich is different than that in the incident beam of electromagneticradiation, and in a propagation direction which is essentiallyundeviated and undisplaced from the incident beam of electromagneticradiation, said compensator system further comprising third and forthBerek-type retarders which each have an optical axes essentiallyperpendicular to a surface thereof, each of which third and forthBerek-type retarders has a fast axis, said fast axes in said third andforth Berek-type retarders being oriented other than parallel to oneanother, said third and forth Berek-type retarders each presenting withfirst and second essentially parallel sides, and said third and forthBerek-type retarders being oriented, as viewed in side elevation, withfirst and second sides of one of said third and forth Berek-typeretarders being oriented other than parallel to first and second sidesof said forth Berek-type retarder; such that in use an incident beam ofelectromagnetic radiation exiting said second Berek-type retarder iscaused to impinge upon said third Berek-type retarder on one sidethereof, partially transmit therethrough then impinge upon said forthBerek-type retarder on one side thereof, and partially transmittherethrough such that a polarized beam of electromagnetic radiationpassing through said first, second, third and forth Berek-type retardersemerges from the forth thereof in a polarized state with a phase anglebetween orthogonal components therein which is different than that inthe incident beam of electromagnetic radiation caused to impinge uponthe first side of said first Berek-type retarder, and in a directionwhich is essentially undeviated and undisplaced from said incident beamof electromagnetic radiation; with a result being that retardation isentered between orthogonal components of said input electromagnetic beamof radiation; m. a compensator system comprised of first, second, thirdand forth Berek-type retarders which each have an optical axesessentially perpendicular to a surface thereof, each of which first andsecond Berek-type retarders has a fast axis, said fast axes in saidfirst and second Berek-type retarders being oriented essentiallyparallel to one another; said first and second Berek-type retarders eachpresenting with first and second essentially parallel sides, and saidfirst and second Berek-type retarders being oriented, as viewed in sideelevation, with first and second sides of one Berek-type retarder beingoriented other than parallel to first and second sides of the otherBerek-type retarder; such that in use an incident beam ofelectromagnetic radiation is caused to impinge upon one of said firstand second Berek-type retarders on one side thereof, partially transmittherethrough then impinge upon the second Berek-type retarder, on oneside thereof, and partially transmit therethrough such that a polarizedbeam of electromagnetic radiation passing through both of said first andsecond Berek-type retarders emerges from the second thereof in apolarized state with a phase angle between orthogonal components thereinwhich is different than that in the incident beam of electromagneticradiation, and in a propagation direction which is essentiallyundeviated and undisplaced from the incident beam of electromagneticradiation; each of which third and forth Berek-type retarders has a fastaxis, said fast axes in said third and forth Berek-type retarders beingoriented essentially parallel to one another but other than parallel tothe fast axes of said first and second Berek-type retarders, said thirdand forth Berek-type retarders each presenting with first and secondessentially parallel sides, and said third and forth Berek-typeretarders being oriented, as viewed in side elevation, with first andsecond sides of one of said third and forth Berek-type retarders beingoriented other than parallel to first and second sides of said forthBerek-type retarder; such that in use an incident beam ofelectromagnetic radiation exiting said second Berek-type retarder iscaused to impinge upon said third Berek-type retarder on one sidethereof, partially transmit therethrough then impinge upon said forthBerek-type retarder on one side thereof, and partially transmittherethrough such that a polarized beam of electromagnetic radiationpassing through said first, second, third and forth Berek-type retardersemerges from the forth thereof in a polarized state with a phase anglebetween orthogonal components therein which is different than that inthe incident beam of electromagnetic radiation caused to impinge uponthe first side of said first Berek-type retarder, and in a directionwhich is essentially undeviated and undisplaced from said incident beamof electromagnetic radiation; with a result being that retardation isentered between orthogonal components of said input electromagnetic beamof radiation.
 16. A method of calibrating a spectroscopic ellipsometersystem as in claim 15, in which the step b. obtaining of at least onemulti-dimensional data set(s) comprising intensity as a function ofwavelength and a function of a plurality of discrete settings of said atleast one means for discretely, sequentially, modifying a polarizationstate of a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation for each of at least twoellipsometrically distinguished sample systems, involves obtaining datafrom at least as many sample systems as are utilized discrete settingsof said at least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation.
 17. A method ofcalibrating a spectroscopic ellipsometer system as in claim 15, in whichthe step of providing a spectroscopic ellipsometer system furthercomprises providing a reflectometer in a combination with theellipsometer system, said combination comprising a spectroscopicreflectometer/ellipsometer system being configured such that apolychromatic beam of electromagnetic radiation provided by said sourceof polychromatic electromagnetic radiation can be directed to interactwith a sample system present on said stage for supporting a samplesystem without any polarization state being imposed thereupon; and suchthat a polychromatic beam of electromagnetic radiation provided by saidsource of polychromatic electromagnetic radiation can be, optionallysimultaneously, directed to interact with a sample system present onsaid stage for supporting a sample system after a polarization state hasbeen imposed thereupon.
 18. A method of calibrating a spectroscopicellipsometer system as in claim 17 in which the step of providing apolychromatic beam of electromagnetic radiation without any polarizationstate being imposed thereupon which is directed to interact with asample system present on said stage for supporting a sample system, iscaused to approach said sample system at a near normalangle-of-incidence; and wherein a polychromatic beam of electromagneticradiation provided by said source of polychromatic electromagneticradiation upon which a polarization state has been imposed, is directedto interact with a sample system present on said stage for supporting asample system at an angle near the Brewster angle of the sample system.19. A method of calibrating a spectroscopic ellipsometer system as inclaim 18, in which at least one of said polychromatic beam ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation upon which is, or is not, imposed apolarization state, is directed to interact with a sample system presenton said stage for supporting a sample system via a fiber optic means.20. A method of calibrating a spectroscopic ellipsometer system as inclaim 15, in which the step of providing a polychromatic beam ofelectromagnetic radiation comprises providing an output beam ofpolychromatic electromagnetic radiation which has a relatively broad andflattened intensity vs. wavelength characteristic over a wavelengthspectrum for use in said present invention systems, said output beam ofpolychromatic electromagnetic radiation substantially be a comingledcomposite of a plurality of input beams of polychromatic electromagneticradiation which individually do not provide as relatively broad andflattened a intensity vs. wavelength characteristic over said wavelengthspectrum, as does said output comingled composite beam of polychromaticelectromagnetic radiation, said system for providing an output beam ofpolychromatic electromagnetic radiation which has a relatively broad andflattened intensity vs. wavelength characteristic over a wavelengthspectrum comprising: a. at least a first and a second source ofpolychromatic electromagnetic radiation; and b. at least a firstelectromagnetic beam combining means; said at least a firstelectromagnetic beam combining means being positioned with respect tosaid first and second sources of polychromatic electromagnetic radiationsuch that a beam of polychromatic electromagnetic radiation from saidfirst source of polychromatic electromagnetic radiation passes throughsaid at least a first electromagnetic beam combining means, and suchthat a beam of polychromatic electromagnetic radiation from said secondsource of polychromatic electromagnetic radiation reflects from said atleast a first electromagnetic beam combining means and is comingled withsaid beam of polychromatic electromagnetic radiation from said firstsource of polychromatic electromagnetic radiation which passes throughsaid at least a first electromagnetic beam combining means, saidresultant beam of polychromatic electromagnetic radiation substantiallybeing said output beam of polychromatic electromagnetic radiation whichhas a relatively broad and flattened intensity vs. wavelength over awavelength spectrum, comprising said comingled composite of a pluralityof input beams of polychromatic electromagnetic radiation whichindividually do not provide such a relatively broad and flattenedintensity vs. wavelength over a wavelength spectrum characteristic. 21.A spectroscopic ellipsometer system comprising: a source ofpolychromatic electromagnetic radiation; a polarizer which is fixed inposition during data acquisition; a stage for supporting a samplesystem; an analyzer which is fixed in position during data acquisition;and a multi-element spectroscopic detector system; said spectroscopicellipsometer system further comprising at least one means fordiscretely, sequentially, modifying a polarization state of a beam ofelectromagnetic radiation provided by said source of polychromaticelectromagnetic radiation through a plurality of polarization states,said means for discretely, sequentially, modifying a polarization stateof a beam of electromagnetic radiation provided by said source ofpolychromatic electromagnetic radiation through a plurality ofpolarization state being present at at least one location selected fromthe group consisting of: between said polarizer and said stage forsupporting a sample system; and between said stage for supporting asample system and said analyzer; and positioned so that said beam ofelectromagnetic radiation transmits therethrough in use; in which saidat least one means for discretely, sequentially, modifying apolarization state of a beam of electromagnetic radiation provided bysaid source of polychromatic electromagnetic radiation through aplurality of polarization states, is at least one rotatable compensatorthat changes the phase angle between orthogonal components of saidelectromagnetic beam of radiation provided by said source ofpolychromatic electromagnetic radiation; and in which said source ofpolychromatic electromagnetic radiation comprises an output beam ofpolychromatic electromagnetic radiation which has a relatively broad andflattened intensity vs. wavelength characteristic over a wavelengthspectrum for use in said present invention systems, provides that saidoutput beam of polychromatic electromagnetic radiation substantially bea comingled composite of a plurality of input beams of polychromaticelectromagnetic radiation which individually do not provide asrelatively broad and flattened a intensity vs. wavelength characteristicover said wavelength spectrum, as does said output comingled compositebeam of polychromatic electromagnetic radiation, said system forproviding an output beam of polychromatic electromagnetic radiationwhich has a relatively broad and flattened intensity vs. wavelengthcharacteristic over a wavelength spectrum comprising: a. at least afirst and a second source of polychromatic electromagnetic radiation;and b. at least a first electromagnetic beam combining means; said atleast a first electromagnetic beam combining means being positioned withrespect to said first and second sources of polychromaticelectromagnetic radiation such that a beam of polychromaticelectromagnetic radiation from said first source of polychromaticelectromagnetic radiation passes through said at least a firstelectromagnetic beam combining means, and such that a beam ofpolychromatic electromagnetic radiation from said second source ofpolychromatic electromagnetic radiation reflects from said at least afirst electromagnetic beam combining means and is comingled with saidbeam of polychromatic electromagnetic radiation from said first sourceof polychromatic electromagnetic radiation which passes through said atleast a first electromagnetic beam combining means, said resultant beamof polychromatic electromagnetic radiation substantially being saidoutput beam of polychromatic electromagnetic radiation which has arelatively broad and flattened intensity vs. wavelength over awavelength spectrum, comprising said comingled composite of a pluralityof input beams of polychromatic electromagnetic radiation whichindividually do not provide such a relatively broad and flattenedintensity vs. wavelength over a wavelength spectrum characteristic.